P.S.: Sorry, I saw too late that you posted this in the D&D section. None of the groups is currently playing D&D. Pre-existing members of group 2 played D&D5 in the past, though (we wrapped up our campaign last year).
I voted 5+, but my group is a roleplaying group, not a "D&D" group. We have played 1e, 3e and 4e D&D, as well as ACKS (a B/X derivative) and some other d20-era games, but lots of non-D&D games as well. (Edit: oh, and we're playing Dark Sun at the moment, which might half count, but we're not using a D&D system for it.)
We did have a new player join within the last five years, but they didn't enjoy the style of game I was running at the time, so they moved on after a few sessions. All members of the current group have been with us for at least five years.
The group has a whole has existed in a stable form, with occasional additions and departures (and returning members), since the late 90s.
I think, although this is just my gut feeling, that one of the primary reasons why people have such differing views on the game has so much to do with this sort of thing - group stability, length of campaign, single dm groups vs rotating DMs. That sort of thing.
I regularly see things that people posit as table problems, and I'm honestly flummoxed at the idea people allow these kinds of things to occur. Pretty much anything involving lack of trust, mismatched expectations, enduring unfun games or people, is utterly alien to my experience. I am also completely immune to any issues caused by D&D dominating the market, have no problems running any game that takes my fancy, and do not in any way rely on WotC, D&D, the industry or the wider community to provide me any kind of gateway for new blood.
I have become aware that all this is basically because I game with friends, and turn friends into gamers as required, rather than go looking for gamers I can turn into friends. I would not have it any other way.