What prevents the implementation of these protocols from leveraging type safety
Global invariants of a running distributed system are different than local invariants in a single program that you can stop, deploy re-compiled binaries to, and then start again.
Now, you can use static types in actor systems, and they are some of these that exist. These typed actor systems don't do all the same things that erlang/OTP does (that may be ok - maybe you don't need them). If your use case fits into what the typed actor systems actor systems provide, by all means, one of those are probably a better fit for you.
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Global invariants of a running distributed system are different than local invariants in a single program that you can stop, deploy re-compiled binaries to, and then start again.
Now, you can use static types in actor systems, and they are some of these that exist. These typed actor systems don't do all the same things that erlang/OTP does (that may be ok - maybe you don't need them). If your use case fits into what the typed actor systems actor systems provide, by all means, one of those are probably a better fit for you.