At my firms I saw this happen often. HR would review, or a junior engineer and pass on very good candidates. It wasn't until I set up a review system with A-class engineers that we started to catch the best people. A-class engineers recognize themselves far better than anyone else. But they prefer to build than review resumes.

I ended up building my own head hunting firm specifically to address the whole pipeline. That helped somewhat but head hunting is its own very odd space. Full of inefficiencies and bias.

With any AI company, there are always limits you hit. Energy, compute, optimizations, inference, team resources, money, and all the flows to make it a company. HR is usually the one that gets the fewest resources.