lsp-mode maintainer here. I may assure you I know how the traditional elisp is written and I simply dont like it. Happily lisps allow you to write in different styles I can tell you that a lot of people find lsp-mode's source code more readable(in addition to being faster). To give an example of the differences in the mindset: Emacs core developers have `first`, `second` and `rest` deprecated in favor of `car`, `card`, and `cdr`. I will do the opposite.
Of course, there are problematic sections (so do eglot) but keep in mind that `lsp-mode` and emacs-lsp organization has ~10 times more code and contributors.
Of course, there are problematic sections (so do eglot) but keep in mind that `lsp-mode` and emacs-lsp organization has ~10 times more code and contributors.