I'll add a Con:
No one tips! It'll be completely pointless, and unused. I haven't come across a single post that someone tipped another person, or gave away coins for free.
(P.s. I'm sure they are out there, you don't have to search the whole forum to prove me wrong. But it's not very common.)
I've seen a few, though they're not very common.
I've offered to tip someone (can't remember who it was) but they respectfully declined because they didn't need it.