The show didn't start out as a massive success. For the first couple of seasons it got little attention. It succeeded due to very smart casting choices.

The role of Moira was written specifically for Catherine O'Hara. Dan and Eugene created it so you can't throw shade at them for starring in their own show. The auditions of the other cast members are online for all to see. Annie Murphy had $3 in the bank when she was cast, and the actor who played Jocelyn had just applied for a job stacking supermarket shelves, so they did support struggling actors. I was always struck by the diversity in crowd scenes, compared with others shows.

The only charge of 'nepotism' that can be made is the casting of Twyla, and her scenes, particularly with Johnny, added some of the sparkle that made Schitt's Creek so special.

Arguing that all shows should have minority quotas and support a political agenda is a good way to stifle creativity.