In fact, I worked on server code for TinyMUCK, and Jonathan Blow was a prominent player in those days, going by the name of Stinglai. Stinglai actually helped create the first TinyMUCK-based worm in the Forth language.
We had added this nifty feature where, in addition to static strings as fields such as descriptions, you could run a program instead. So it was like "#!/bin/bash" in a shell script; we called it "@#" because you just entered "@#xxx" where xxx was the database ID of the program you wished to call. So it was really flexible and programmers enjoyed generating dynamic strings instead of the static ones from before.
Of course we had no authentication or permissions system to protect players from one another. Every program ran under the credentials of the user who called it. Now by putting this in descriptions, a player could unwittingly call a program just by looking at something or someone.
Needless to say, this was ripe for abuse and immediately turned into a pernicious worm, where anyone who looked at anyone else became infected with the same "@#" description which was designed only to propogate itself through setting of descriptions. If I remember correctly, it only propogated among players, and not objects or rooms, because it needed to be actively called by someone "look"ing at a description.
I can't remember if, when or how we settled on a solution for that, but it sure was a wakeup call.
I don't think Blizzard profited from either of those. As far as I'm aware, their only paid WoW product at the time was monthly subscriptions to the game -- there was no officially supported way for players to buy in-game currency, and players paid Blizzard the same amount regardless of how much time they spent in game.