Want to install PyTorch? which one? CUDA? Oh, OK, then you have to get the wheel directly from them because there are 6 different versions for differnet CUDA versions, and the wheels are too large for PyPi anyway.
Conda offers only a partial resolution to this problem. Spack is great at being ultra configurable and having all the C/C++/Fortran dependencies and compiler toolchains you need, and so allowing ekeing out best performance, but doesn't integrate well with uv etc. so it's difficult to take an experimental ML project written by a researcher and take it through to productionisation with it.