@rdipardo well, all of the above. But in truth there probably needs to be some benchmarking done, and don't forget I said ctags too. On this X86-64 system the current liblexilla is 56Mb, I wonder how big all lexers would be. But libctags is only 10Mb, I guess thats due to many languages skipping statements and expressions that Lexilla has to understand. Not sure what the mappings would be, and memory usage, at least some configuration isn't loaded until the filetype is needed, but all Scintilla mapping is hard coded ATM and ditto ctags.
And of course the UI is cluttered by all filetypes ATM, and there have been reports of the filetype menus being too big for small screens, which is unfixable since menus can't be scrolled onto the screen. It has been suggested to fold those menus alphabetically, see my link to wikipedia above to see that would be better.
Some of the paranoia was triggered by the request to include the uctags peg parser for TOML and kotlin, TOML compiles into 5000 lines of C but kotlin compiles into over 20000 lines, but I guess again we need benchmarks how big they are compiled.
Also note Notebook++ does not run on Raspberry Pis.
Ultimately I can't make up my mind if its really an issue or not because on this development workstation it definitely is not :-) but I can't tell about smaller systems. So since its not undoable once a language is added I tend towards minimising languages that don't have lots of contributors since we don't have the expertise or resources to support many languages (including current ones :-).