If I had the energy to argue it I would also argue against using TOML
in those PEPs.

I partook in that discussion, and I still have no idea why TOML was chosen, over, say, a defined subset of YAML, or a slightly extended JSON. 

But the folks that were highly invested  and putting the work in made a choice, so here we are.

 But if it’s in the PEPs, it seems time to define a version used ( 1.0 would be good, but often that’s actually pretty arbitrary) and get an implementation into the stdlib. 

If the TOML folks don’t think it’s stable enough for that, I’ve got to wonder if it was a good choice! 

We’re have enough trouble with really slow adoption of the new ways of doing packaging, not even providing the tools seems to really defeat the purpose.