Does end-to-end have to be agnostic to the backend to you? Do you feel the same way about end-to-end encryption? Would you say "end-to-end encryption as long as

Does end-to-end have to be agnostic to the backend to you? Do you feel the same way about end-to-end encryption? Would you say "end-to-end encryption as long as the backend is rust/go/c"? Why not, what's the difference? Most projects exist in a ecosystem, and in this case using the same language on both ends makes total sense don't you think? They pull from the same repository, use the same language servers, and run mostly the same code. Why is that a problem?