I've heard people be completely open about only wanting to mingle and network with "peers", where they'll immediately ditch people at networking events / parties / etc. if they're not up to the snuff. They'll ask what school you went to, or where you work(ed), and bow out if its not a target school or top-tier firm.
But people like that are a minority in my experience. I went to a good business school, and many people there had the same background stories - especially the type of undergrad schools they went to.
(With that said, I'm pushing 40, and every now and then I do meet new people that within 2 mins will ask or probe what school I went to. Always feels a bit weird to me to bring up alma mater when it's almost half a lifetime ago...especially if those asking are even older than me.)