The point is this exploit, according to the researchers, required massive and unusual manual intervention by the user, so it's very different from the other exploit you mentioned that involves millions of auth attempts

From the link I just posted, written by the researchers:

'Nevertheless, on the clients that we analyzed, all attacks would have required a substantial number of manual login attempts (i.e., the user entering the password). Since clients usually cache the credentials, users often stay logged in, minimizing the number of logins performed and thereby increasing the difficulty of the attacks.'

That's his/her point, right?

  >  I have a Mega account and I think I've logged 
  > in less than 50 times in the entire lifetime of my account...

I also have a Mega account, and my experience is the same.

You know a million times more about cryptography than me, but it doesn't change the fact that I, personally, am not compromised by an attack that requires me to log in that many times.