Understanding has always been the bottleneck. That's why LLMs aren't actually helpful: they speed up the part which is easy (typing characters into your editor), but are neutral or even harmful on the part which is hard (understanding the problem and how best to solve it).

It seems like humans have a limited "understanding budget" but LLMs force us to spend that understanding on waaaaay more code and projects than ever before.

The part which is easy is still time consuming, so LLMs are helpful. They're just not a silver bullet.