The reason I say it can't hurt them is because generally, the players are going to find methods to do things like that anyway, so if SE drops the banhammer, all they do is lose subscriptions that were paying money, even if they were not doing much in terms of actual play. Instead, they could allow players the limited ability to conduct business via an authorized assistance channel, paying commission fees to veteran players for their services. Something like 1 dollar per 10,000 exp aquired, or 5 dollars for a mission battle completion along with all rewards going to the customer. Takes away some of the competitive edge of selling items like that, which in turn could help adjust the fucked economy in some games. Matter of fact, assigning the drops to the player in a fashion that they couldn't be sold after would even fix it further. This is pretty simplistic to me, as I know it's fully possible to do a fixed to player thing ( ex items in ffxi). You could even leave the non- assisted versions as free to sell, giving players incentive not to pay to win. It's pretty common knowledge that if you make bad things acceptable, people tend to not use them as often, or generally don't go beyond the one bad habit.
Obviously I am no business graduate, but for a company that's losing money because its playerbase is getting annoyed at their bad decisions, maybe they should cater to the fans more instead of assuming they know better. I can't say the same about blizzard or bioware or other mmo developers maybe, but the people who play those types of games are pretty similar between titles. What works on one should work on others. But meh, who am I to call out these asshats, eh?