for a non-technical user, this is a security flaw. You buy a tablet, activate it with your gmail account, and next thing is your private email is exposed to your party guests.
For non technical users the browsing history gets exposed too along with chat logs... I would be a lot more worried about those. Basically the problem would be the lack of guest accounts or guest mode. Every time I let someone use my laptop for browsing I open up an incognito window in Chrome.