I'm getting the same vibe here. I've had this happen to me before, when I interviewed for a smaller company, and they were literally offended that their offer wasn't the only one on the table. When I told them I already have two offers, the hiring manager very politely scolded me about it, saying that they prefer candidates who apply to their company and their company only. I usually find this type of exceptionalism very amusing and had no shame in sharing my feeling with the guy.

For the past couple of years, I noticed this trend of trying to fuck over prospective employees and drive down compensation. Of course, we can't forget the no poaching cartel for which large companies got a nice slap of the wrist, but it's the small things like:

- rejecting candidates with competing offers (like OP above) - not providing offers in writing (so that it would be hard to use a verbal offer in a negotiation) - requesting written proof of competing offers or paystubs to prove current income. - prolonging or spreading the interview process over weeks/months so that you're not able to coordinate negotiations (Google is a major offender here).