At least with an Opus we know why we don't see you around without wondering if you got hit by a car (or went off a bridge with a fat Senator driving). I think stating general reasons without whining about specific events or individuals is considerate as well. Best wishes.
It can be deceptive. People who aren't familiar with the circumstances don't know that gopc used a lot of the tactics he's crying about now on other people. Thus he gets condolences from people who are writing about their own experiences, not his. He was quite savage when he wanted to be and if there has been a decline in standards during the time gopc was posting, he's as responsible for it as anyone else.
I'd recommend people google some of his Civil War posts to see his tactics at work. His old posts won't be pleasant reading but do provide the context in which to understand his parting shot, which certainly doesn't avoid what you call whining. He did his bit to make FR more contentious and bitter and simply objects to what he started coming back around against him.
If you do a little digging you can come to your own conclusion, but gopc was very much a disciple of Thomas DiLorenzo and his belief that tariffs were more central to the cause of the Civil War than slavery, and he was quite vitriolic and vindictive in pursuing his obsession, conceding nothing to those who disagreed with him. Love of the Confederacy and hatred of the tyrant Lincoln were something approaching a religion for him.
It's not so much what gopc said, as how he said it. He was convinced that his enemies were scoundrels and he was breaking the back of their argument with his latest personal attack, bit of jargon, condescending remark, or factoid plucked out of context. A little of that sort of triumphant nitpicking and name calling goes a long way.
Gopc's style of argument was counterproductive and did a lot to convince me and others of just how wrong-headed DiLorenzo was. After enough time passes one can look back fondly on a lot of people and things that one disliked at the time, but right now I don't regret his leaving.
I don't think he'll leave us much time for that. By leaving on his own, rather than get banned, he has the option to come back, and sooner or later he probably will in one guise or another, and with all his dogged persecutorial zeal, perhaps in response to this very post.
In general, whenever somebody offers a "they" have taken over and are pushing "us" out screed, it's a good idea to look up the facts of the matter, and not simple to take the accusations at face value. Specific issues or specialized disputes get turned into great ideological battles in such opuses, and people who did more than their share of abusive infighting may pose as martyrs in their swan songs.