Merc'ing existed before all this recent stuff. Hell, the Salvage bans were pretty much predicated on holier than thou people doing it back in the day while exploiting the loot system. It also existed in other forms like Hakutaku fights, ODS KSBCs, Dynamis clears, and more. It's also rather disingenuous to assert that people taking advantage of this lacked friends or social connections, when I could easily suggest they all couldn't play at the same time, had incompatible job combos for whatever particular event, were in different phases of progression, and so on. There's no hard and fast rule that states anyone that shares in suffering through some event winds up a buddy, either. For every good player we may have met, there were countless others we actively forgot due to mediocrity or intentional dislike. As is the common risk with group content, however, the more bodies you require, the more difficult you make it for people without an active, organized group of their own. And that's before factoring in things like job discrimination in focus, where you might not have had people really interested in farming Shen for Reverend Mails for WHMs, but if it was something they could've personally benefited from? Different tune. Lord knows I had to endure the "Just solo it!" mentality on RDM whenever I'd ask for help to make things go more quickly and safely.
So, yeah, let's not pretend everyone is suddenly socially inept and that this is really just MMO equivalent generational "Get off my lawn!"-ism. People hate wasting time. That wasn't new then, and certainly not now. Unfortunately, to counter the merc game, players actually need better tools at their disposal to hook them up with like-minded players across the multiple servers. A few shouts now and then probably won't cut it. People in more established groups are also less likely to take in a random newbie to be nice. No, they're going to want equally geared/skilled or better players to make their own profitability rise for the activities they want to do in their time. Otherwise, you pretty much need those obscene amounts of gil to coax them from their own little circles. The harder the content and rarer the drops, the worse it gets.
That said, RMT never is, was, or will be beneficial to the game, as there is a high probability that anyone who did partake were simply lining the coffers of those that created the financial problems to begin with. Would we have never had sushi on the AH without them? Maybe not as cheap, but you also had make fishing a profitable activity legit players would actually want to do. Same for shihei or whatever else basically boiled down to mundane, repetitive actions in order to produce. Bonus points if they could cheat to do it like bot or position hack. The actual complexity of the task was very rarely a concern with those in mind, too. Sure, we maybe had a laugh about how long it took RMTs to kill Kirin or something, but they were still doing it. And keeping us from doing it at the same time. To otherwise imply it's impossible to handle them comes off more as a lack of willingness to try. And it's not just about reacting. It's also about creating environments where they can't thrive. And as long as things like RMEAs exist in XI as a pinnacle, RMT will always have a calling. I'd say SE dropped the ball here by not phasing them out with Adoulin's launch.