There are 1.5+ billion gmail users. I don't have stats, but that intuitively means millions of vulnerable people who could be scammed or phished or whatnot because they would never think of using 2FA at all.

Among those half a million homeless, how many use gmail and are unable to change for whatever reason? Among those, how many have issues with 2FA? Thus we advocate for increasing the vulnerability of millions to do something that would not even help the homeless that much. The whole problem of having to replace their phones every 12 weeks sounds like a far more pressing issue to investigate and find solutions for.