[formalsystem]

There's different tradeoffs, spinning up a separate repo is what we call "out of core" vs having everything in PyTorch "in core"

Basically PyTorch is a large library where CI takes a long time to run which means merging code is hard and adding new dependencies is challenging and there are stringent constraints on BC breaking changes

Instead what torchao did and many other repos like torchtune, torchchat, torchtitan did was move out of core and it helps keep the core PyTorch library leaner with a smaller binary size and it really lets the team "out of core" focus on optimizing for their needs

Unfortunately the argument for what gets better changes over time, for example torch.compile initially a new repo called torchdynamo was built out of core to move fast but eventually merged back because everyone wanted to use it. Now torch.compile dev velocity is still quite fast and so now we have to tell people to use nightlies instead of official stable releases to which some people have asked me why don't you move torch.compile out of core

My 2c is the ecosystem will be much stronger and teams can move faster if they develop out of core so that's the tradeoff we picked for torchao. We managed to for example merge a few custom CPP kernels like fp6 or Marlin that would have challenging to motivate in core since those are still quite experimental and need to stand the test of time.