Yet my point is the converse of this: by not supporting those things, it means for something to be well packaged as a tarball, it may not have any external dependencies nor may it have pre/post installation hooks. And that's a Good Thing.
Because why would you need any of these things?
And how can you survive that level of complexity when the thing in question is itself the build tool which is traditionally the thing that we use to handle these complexities?
This may just be "my opinion", but I think my build tool should have packages available which have no further recursive dependencies -- the buck has to stop somewhere -- and it certainly shouldn't need post-install hooks for absolutely any purpose -- what would it use them for? Doing something stateful? That's antithetical to the core of what a good build tool should be doing.