Of course it’s possible to be effective with different tools but I find even Emacs is made a lot better by Flymake/Flycheck and Eglot.

I like the fzf and rg integration. And some custom elisp (especially for codegen).

i usually don’t use LSP myself most of the time, it’s just a heuristic.

in $current_year, LSP is considered an important part of a language’s ecosystem.

if there are glaring issues with it, something is seriously wrong- maybe the language itself has performance issues, or tiny userbase, etc.

I would say Haskell LSP is considered unimportant by a nontrivial amount of Haskellers. I know of many who just don't bother using it at all. So in the Haskell community, LSP is less important than LSP is in other language communities.

I don’t think GP’s point was that you have to use an LSP server to write serious projects. Rather, the quality of LSP support is rapidly becoming a good proxy for the overall state of tooling for a language (and, arguably, good tooling is a good indicator of suitability for large projects)

That out of the way, I would suggest that you do give LSP a try. The beauty of LSP is that it doesn’t care what editor you’re using, so you can just use lsp-mode and get going.

Oh I have tried it. I didn't use it much, and it made it even more clear that the minutiae of reading and writing code is nowhere near a bottleneck.

What makes something suitable? The tooling and language servers around Python are atrocious, but it is nevertheless very widely used (including among academics, arguably one of the more serious fields. Of course it also generally produces absolutely garbage code, but I don't think that's the tooling's fault).