1. People are bad at making new passwords 2. Someone might clear their browser history and delete the logins as a result. 3. Lock-in into the Chrome ecosystem.
I personally use KeePass, but I understand it is a bit cumbersome to carry around a USB stick.
I'd recommend LastPass to those who don't understand simply because it has a free tier, but everyone else should seriously consider paying the 2$ a month for whichever service they use.