Description
Plots and diagnostics are still accessible via PyMC3 but are actually implemented by ArviZ now. Although this was a good call when ArviZ was still nascent, now this causes confusion for new comers and overhead for devs, who have to mirror the functions in ArviZ, which is more work when ArviZ adds or changes functions (e.g pm.hpd vs. az.hdi).
To make all this more robust and easier to maintain, we should completely remove plots and diagnostics from the PyMC code base and rely on ArviZ, since the latter library is now much more known and flies on its own (yeah, I'm a part-time poet).
The coming 4.0 major release is an opportunity to make this breaking change -- plus, it'll make the code base cleaner and leaner 👌 Feel free to comment if you wanna take on this issue 🖖