This is something they hope to be true, but they probably know to be false. If you already know it to be false, then it's a lie.

Someone pointed out you do get to know your coworkers better, but I'd argue you just get to know them better, faster.

Again, any source for that? I get the feeling it's actually the folks speculating that it's about money who are hoping that to be true, cynically.

Cornell did a study that showed that people interact less when they have offices. Their definition of "frequent interaction" dropped from several times a day ad hoc (with open plan) to several times a week in a meeting. That's some data supporting that it does in fact improve collaboration.

Archive.org is down right now but I can supply a link to the study later if you want.

Yes, this is known as a "lie".