It's more simple than that, nothing psychological.

When you're in a top-down Imperial society that demands all peons contribute back to the top for the survival of the Glorious Government, anyone that isn't contributing back in a meaningful manner is looked down upon as a negative. Entertainers pretty much fit that bill when you think about it, as they're rather extraneous to human survival.

If it truly is the "they can pretend, so they're untrustworthy" mentality, might be more of the average person's lack of understanding the ability to compartmentalize. I don't think all of pre-Industrial era acting had the same kind of problems Hollywood and beyond acting had too. The concept of celebrity didn't really reach it's modern emptiness until mass media became a thing.

burakkumin

The noting of "gravediggers" should point to that it wasn't a full-proof idea in Japan. To my knowledge, this "caste" includes animal butchers, a profession that can also be necessary to society. IIRC, depending on the region this attitude is still practiced to this day.