And the third is that they leave their keys in their coat. When I’m at home, I leave my keys (and therefore my yubikey which is on my key ring) on my desk and when I’m out, I always keep them on my person and never unattended.

So that leaves ease of setup and support. Since setup only has to be done once per site, and I only bother with important sites, that’s not a major deal for me either.