Why does Google suck so bad at building great user experiences?

Let’s say I want to manage my gmail or google or youtube avatars, however they set it up (honestly, I don’t know where the photos end up), how the heck do I do that? If I want to switch back and forth between multiple gmail accounts (e.g. business, etc) on a desktop, how the heck do I do that without having to use ALL the google products under one single user account. Say, I want to check my business emails but I’m watching youtube with my personal user account. It kicks me out and start using my business account on youtube. The list goes on and on...