Yes it can be set up, but my point was precisely that it(LSP servers for popular languages) is not baked into Emacs, instead making them complicated external dependencies necessary to be set up to get a basic IDE functionality of code completion working.

Code completion works out of the box for example in IntelliJ for example without needing to download and install further packages.

The tree sitter approach does sound something along in that direction, that should bode well if it works out.