They can't do anything elaborate or interesting for me beyond literal tiny pet project proof of concepts. They could potentially help me uncover a bug, explain some code, or implement a small feature.

As soon as the complexity of the feature goes up either in its side-effects, dependencies, or the customization of the details of the feature, they are quite unhelpful. I doubt even one senior engineer at a large company is using LLMs for major feature updates in codebases that have a lot of moving parts and significant complexity and many LOC.