Because it doesn't perform as advertised: wild amounts of inconsistencies in behavior (within and between versions), performance issues (pnpm exec adds 15s to all shebang'd execution time over npm/yarn/bun/etc.), etc. Version-to-version stability has been traditionally bad - it's half-baked software.

Claude doesn't know this, of course, because it can only read superficial summaries posted on the internet and has zero real experience actually using this dumpster fire.