"Porting for donations"...a little selfish?

[Jingleson]

Now I realize it's common courtesy to tip someone for buffs, revives, and ports. I always tip when I ask for any of these services (what I can afford, anyway), but the point is that it's technically a free service from most people and clients don't HAVE to tip if they don't want to. It's extremely petty and tacky, but they don't have to.

But I've run into a few people now that say things like "Porting for donations, at least 25pp" or "Will buff for tips." which gives the impression that they won't port you or buff you unless you give them a donation, turning a complimentary service into a paid one. I've even seen a few cases where newbies have been turned down for buffs or ports after asking politely for one, and I get the feeling it was because the people they were asking knew that they were broke and likely wouldn't have money for a donation.

Don't get me wrong, I'm all for tipping someone who spends their time and mana to help you out, I always tip when I can, but when did donations turn into a MANDATORY thing? When did people start acting like "no donation? no port."?