Regional jets allowed airlines to service smaller markets. An E175 (or a CRJ700 and others) takes up as much space in the departure line or the alley as an A320 or B737, but that E175 has half the seats. You couple that with ATC still largely reliant on RADAR to manage planes in the air and it is a huge mess. Airports are at capacity every day. Even a small event causes significant delays. Ground planes for a few hours? It is a veritable disaster that takes a week at least to get planes repositioned.

I was on the road for 6 to 9 months a year for a couple of decades. My role changed during COVID and I don't miss traveling at all. I don't miss stressing because there are clouds in the sky. I don't miss the frustration of missing an earlier flight by 15 minutes because of bad setup for security. I don't miss sitting in an aluminum tube on the O'Hare tarmac during summer on an RJ that has lost its APU, so no AC. I don't miss surly passengers who make it awful for everyone. I certainly don't miss hotels that have stripped away all service and convenience, including actually cleaning the rooms decently. I don't miss how I was forced to compartmentalize my life between on the road and at home. The only thing I sometimes miss is some of the good meals I was able to have with work friends.