For 1 , we had multiple bishop events (Noel and Paula for example - which are both decent) , so many people have those at max crs. There is also the fact that dps wise , the difference between bishops , and mages its not THAT big....as well as bishops having a bit of a longer range (so they can be deployed in more restricted spaces) , and they can heal as well , so that makes them more versatile...

i'm guessing you're also seeing plenty of videos with Noel. The difference in dps is not that big to matter most of the times. People simply use noel because her AW passive boosts the gold dropped by 10%.