70D and 80D are used for vlogging because they provide the excellent Canon Dual Pixel AF which is important for one-man shows, especially daily vlogs. Panasonic GX85, Olympus E-M5.2 provide better image quality and stabilization but do net get the AF-job done. The CDAF implementations are simply not reliable enough. You do not see the focus hunting in the small flip-out screen during recording. Of course there is obvious stuff, where the camera focusses on the background an is not willig to change but the problem are the small, nearly unnoticeable glitches, when the face tracking loses the face for a fraction of a second. Once back at the NLE you realize that it looks awful but today's episode needs to be pushed out ...
Vlogging is a growing business, pobably understimated by poeple that are not used to it. A lot of money is involved when the number of followers get over one million and while content is still king the quality level is quite high.