Blades in the Dark, a game I have many opinions on, presents a "game mechanic" it calls progress clocks. I have seen this "mechanic" often cited as a great innovation in the TTRPG genre, and is often discussed as one of the best components of the game. Although I do not deny the functionality of progress clocks, I argue that they are merely a tool and not deserving of the term game mechanic. Nor do I think that they are particularly innovative.
Clocks, as presented, are a system in where the GM creates a circle split into a number of equal parts, and fills it in to track information. It can be read about in more detail here. The rules describe the many uses of clocks - they can be used to track nearly anything by giving one a name and filling (or unfilling) the parts. I do not deny this at all, but I don't think it is also a particularly impressive feat when we consider what a clock actually is.
Let us, then, delve into how a clock functions.
The clock is split into N parts, which can be filled (or unfilled potentially), upon certain triggers. When the clock is filled, this represents something in the fiction occuring. There are functionally two triggers for a clock to progress:
Case (a) is nothing new. I do not hesitate to say that this has been a method used in TTRPGs since their very inception. Because, if we look even a tiny bit closer, it is just counting success/failure - and incrementing or decrementing an integer. In prior RPGs, this may not be in the form of saying "this is a clock" but instead "you will have to succeed n times" or "you will need to do x, y, and z to accomplish the task" etc. It is just changing an integer. HP is a form of clock, really. In fact BitD doesn't even really understand it's own idea: the Stress mechanic is literally a clock, but is not represented in that way.
Case (b) is equally uninteresting if we consider it in relation to every TTRPG that has ever been played. If the clock progresses at the GMs discretion, then it is not a game mechanic, it is merely a representation of a status. One of the uses presented for clocks is to track the relationship of the players to some other party; "When the PCs have downtime, the GM ticks forward the faction clocks that they’re interested in." Mechanically, this is nothing - this is entirely meaningless; this is just a way for the GM to show the players what has changed - but these things have already happened regardless of the state of the clock. You may argue "but the players can decide to try to reduce a clock they don't want filled" which is true, but they can do this anyways. Let us imagine a clock called "War with the Cheeseguards" - when it is filled, the Cheeseguard faction becomes actively hostile to the players. In a game with the clock, players will say "We should [do something] with the Cheeseguards to reduce the Clock." In a game without the clock, the GM would say something such as "The Cheeseguards seem to be getting more hostile towards you" and the players may say "We should do something about that, we don't want the Cheeseguards to go to war with us, that would be bad." Both of these cases result in the same things occuring in game and in the fiction - however I posit that the case without the clock is actually more interesting and has a better roleplay aspect.
This last example brings me to one of my main gripes with the clock mechanic (which is also the case for a few other "mechanics" and "innovations" of BitD, and my main issue with the game overall). It strongly gamifies an aspect of TTRPGs that is otherwise a naturally occuring part of the game. I think this can be mitigated with good usage of clocks and a good group, so it isn't as egregious as, for instance, position/effect (which I will likely rant about on another occasion). In many cases, I think a clock is an unnecessary tool which is used to brute force something that will happen naturally anyways.
All this said, I do not think clocks are bad - I do often use them in my own games. I just don't think they deserve to be called a "game mechanic" nor do I think they are particularly new or impressive. What they are is a good tool for representing progress that can be tracked with integers. When it makes sense to have something tracked with integers (incrementing or decrementing) and it is useful to display it in a quick to read way, clocks are in fact a very good tool. But, this is a GM tool to be used when appropriate, by ingraining the idea into a game as a "mechanic" we incentivise their use when they are not necessarily appropriate or useful - and we warp the game and fiction around the idea of incrementing and decrementing integer values, rather than doing things in the fiction (in a self professed "fiction-first" game, to boot). If this idea was presented in a GM advice section I would have absolutely no issue with it, but it is presented as a mechanic - and it just isn't one and can't be.
I do think that this may be a consequence of video games. In a video game, a very different and much more restrictive medium, clocks would be a mechanic. This ties back to the gamification aspect. In a video game, these sorts of displays of the status of the world are necessary, as the video game has no GM and lacks the ability to effectively communicate this information through simple discussion and exposition. In a video game, these changes need to be codified and strictly defined - they need to be heavily limited. This is what clocks seem to do in many cases: they codify the nuance and depth of the games conversation into a simple integer. This simplification, while necessary for a format with very limited means of communication and adaptability, is an active discarding of the strengths of a TTRPG. I have, in prior discussion, been told that clocks (for the currently discussed reasons) make it easier for people to learn to play TTRPGs. This may be true, but they do so by letting us treat the TTRPG as a video game. We may be able to easier sit down and play the game, but it incentivises merely emulating video games with the added layer of "saying stuff" as opposed to playing into the real strengths of the TTRPG medium.
Clocks are just counting; nothing more, nothing less.