The issues is that you get benefits for sticking to one paradigm, because then everything is made of the same stuff.

If everything is an object, then you can use all your tooling that works with objects, which is everything. If everything is pure, you get easy parallelism. If everything is an actor, you get easy distributability. If everything is a monad or function, you get easy compositionality. The list goes on. Smalltalk, Erlang and Haskell are languages with very dedicated fan bases, which I theorise is because they went all in on their chosen paradigm.