I run https://bye-tracker.net and am also working on https://lanes.pm (still closed beta but open for more users soon). I just retested all of them and it really seems none are fully usable. I also see few improvements since April, it seems many of the teams either burned out trying to finish in time, were overwhelmed seeing what it really takes to make the details work after the fun parts are over or were disappointed seeing how low user numbers are from direct switchers.

I disagree with your 2010 theory, back then it would have been even less fruitful to make a viable alternative with the limited time and resources available. Especially as things like the UI state handling and some of the architecture was unheard of back then, years ahead of its time and even linear now does not fully match many aspects.

Similarly "Any half-skilled indie dev could have made a killing on making a good replacement" is just wrong, a) you need to be a really great developer to make something that even nearly matches PT, there is more than is obvious to someone not deeply familiar with the internals of the product and 15 year of refinements that went into it. A few of the cloning teams were some of these indie developers who thought it would be fun and easy which was obviously very naive.

b) "Make a killing" is equally misleading. I would be surprised if its possible at all to break even on something like a pure PT clone. There are maybe 200 original users who are super loud and "in love" but this can easily mislead to thinking there are millions of users that would be immediately jump on and start paying. It takes probably 2 orders of magnitude more addressable market to make the financials work just by providing a PT clone (Which is why lanes.pm is focusing on making what tracker would need to be today not just catching up on what it was.)

Just give it a bit more time, there are at least 2 teams including lanes working on this and we all decided not to launch something half baked and buggy that loses your data.