Such achievements are really more of a mark as to the tribe's success than the player's. Maintaining the same people in a tribe together for 180 days is an impressive achievement of stability in a game seemingly designed to create instability. There are not a lot of tribes that can do that.
It's important to remember, though, that long-term success in TW is not about skill. It's not about activity. It's not about loyalty. It's about persistence. It's about keeping playing in any circumstances, the good and the bad. The interesting and the boring. In the long-term, it doesn't matter if you have the best stats, or even what people think. It matters that you get results.
Long-term success is not an easy goal. It looks easy on paper, but in reality, it tests skills most people don't have. Frankly, I'm not even certain I can succeed long-term. Being successful in the long-term is hard enough for a player to do. For a tribe, it's almost impossible. In my opinion, it's the ultimate achievement in TW.