1:1 adds value if the managers spends most of the time actually managing and 1:1 is a place where he gets part of input for that. 1:1 with lead that spends most of the time doing 1:1 is pointless

> what is the job you think line managers are supposed to be doing, if not listening to devs, going to meetings you would prefer not to sit through, and writing up carefully documented feedback for the under-performers you seem convinced surround you at every turn?

Actually managing. The listening to devs and sitting on meetings is pointless if you are not actively using those meetings to organize, prioritize, plan and execute parts of plan.