It’s more than web.dev simply being owned by Google, at times the site feels like content marketing for Chrome and not just a resource to learn about web development. I’ve seen them post multiple articles about the latest Chrome-only updates, while I’ve never seen MDN promote content that only focuses on Firefox. Not to say MDN has never done that, but at least to me, web.dev has a definite Chrome bent that you wouldn’t expect from the way the site initially presents itself.