[talmand]

I'm thinking he meant more in terms of who builds a website that respects the "like Gecko" in the UA string as UA sniffing has been considered a sub par method for a while now.

I agree with "who does that" because I've never done UA sniffing so I had to look up the term "like Gecko" to even understand the context. As someone else has pointed out, that's for browsers that are not using the Gecko rendering engine. So essentially, everyone is trying to be "like Gecko" in one way or another.