We're already seeing RMT spammers in general chat, and out of habit (from WoW) I right clicked on their name in the chatbox but found no option to report them for spamming.

To give you an idea of how this worked, gold sellers in WoW would spam general chat much like here. The devs implemented a function through the chatbox where if you right-click on a person's name you have the option to report them for spam and blacklist them. Reporting someone for spamming caused their text to no longer show up for you for a predetermined amount of time, and Blizzard tended to react to how many spam reports the person received, among other things.

This in effect killed two birds with one stone simply because you were no longer seeing the spammer's text while also notifying the proper people about the person spamming; the moment we would see a gold spammer pop up I'd right-click on their name, click on Report for Spamming and continue about my day. You guys might want to consider implementing something similar, if only to make general chat more bearable.