Perhaps I'll provide a contrary view. I was also at Neurips, and I'm also a junior researcher. Yes, it was massive, and the poster sessions were crowded.

However, I was still able to talk to everybody I wanted to talk to - often for long periods of time. Many of them I sent emails to, and I was able to talk with everybody I wanted to (except 1), many who would be considered senior researchers.

Disseminating scientific ideas is really only one part of what a conference is meant to do. The other part is networking, and that was extremely valuable for me.