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.
You don't really get easy parallelism, do you? People used to theorise this, but auto-parallelisation never really worked because it's hard to understand - even for a machine - where the cost/benefit tradeoff of parallelism starts to happen. Applying a pure function to a massive list is simply not a common pattern outside of things like multimedia codecs or 3D graphics, where these industries settled on explicitly expressing the data parallelism using SIMD or shaders a long time ago. Functional languages have nothing to add there.
It's true there are benefits to working with in one paradigm, but I find that often you can only do this for so long. This is why you have things like redux-thunk.
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.