What happens if you need to change computers?
You mean like I do multiple times per day?
What happens if you need to wipe that one?
I bought a new dhromebook recently and it has all my passwords on it already. MAGIC!
Or you lose it or it gets stolen?
The simple answer is that if I'm logged into my dhromebook and it gets stolen and the thief doesn't let it go to sleep, I'm fucked anyway because they have full access to my email and anything that I can log into via Google. If I'm not logged in or it goes to sleep the worst thing the thief can do is wipe it and log in with their own account.
If someone manages to steal my desktop computer without me knowing, I have worse problems.