Looking at it from another pov, would the people who don't feel like teaching and lecturing even accept a total newbie under their supervision? Unless a person feels like teaching someone, they likely don't want such a burden on their back. It's likely most of the genuinely coolest heroes won't accept trainees, aside from special circumstances (somebody they know, etc).

It was weird to watch this episode, 27th ep, and see Izuku finally realising he needs to fricking train and master his power. That should have been like episode 4 or something.