Kinda complicated. Before the widespread use of the Internet, travel agents played a much bigger role in travel arrangements.
As far as I'm concerned, "loyalty" is pretty valuable. Preferred check-in, preferred security, access to better economy seats, (better) ability to upgrade to business/first class, bonus RDM, airline lounge access, preferred service in IRROPS... these are worth something -- especially as travel hassles have increased, because of higher yields on airplanes, TSA nonsense, etc.
I have gold status on Marriott (earned) and Hilton (gifted). These are nice too -- complimentary Internet access, access to executive lounges. Sometimes I get room upgrades, though I don't care about that.