Yeah, a standard knotless knot hair rig will catch you fish....but there are many situations where a more specific rig will catch you more.
I do see your point though. There are a lot of peeps who will chuck a rig out because they saw a 'pro' do it in a mag or on the tele without really thinking about why they're doing it and if it really suits their water and situation. But if you think about the rig and how it works more and fish it effectively then I think the vast majority of them will give you the edge over the old-style standard hair rig.