On mobile clients they can be quite convenient though. No need to remember any password and good protection against shoulder-surfing.
Relevant: <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=ybNWOhI-Q-4" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=ybNWOhI-Q-4</a>