It's not the only cause but empire building[1] is a very real phenomenon. Maximum viable features is a very interesting concept but it's just that, a concept, nobody says you have to stick to it, it can just be a tool in your toolbox to limit scope creep. One thing I don't have too many of is tools to limit scope.

> the punchline is that they're all using a different 20%.

You could try creating different products.

1. https://www.investopedia.com/terms/e/empirebuilding.asp