I think what's not being acknowledged by people that are against this idea (mostly forum mainers, because I can't think of a single established player that disagrees with the idea of a qualified thread) is that after a certain point, discussion on a suspect is necessarily subjective and based on the qualifications and judgment of the person posting.
There are certain things where it doesn't matter what Elo you have, what GXE you have, how many trophies you have etc because they are factual or objective. If 98% GXE God Pokemon Player started posting about how Kyurem has 500 base SpA, that they have 98% GXE has no bearing on whether or not they're wrong (they're wrong). And if I, a lowly 65% GXE peasant, posted and said "that shit's wrong," my low ranking would have no bearing on whether or not I was right. Because it's just factually wrong.
But when a Pokemon is being suspected, not quickbanned by the council, there's enough ambiguity into whether it's broken/uncompetitive/unhealthy that it's left up to voters to decide. There is no right or wrong answer, it's left up to democracy. So if 98% GXE God Pokemon Player says "in my experience, it's true that you can't really defensively answer Kyurem. But it's adequately addressed offensively through many of the top used mons forcing it out and its more immediately threatening sets being very vulnerable to rocks. I'm voting DNB and if you qualify, I think you should too," that they have 98% GXE lends a lot of credence to their argument. And if I (65% GXE lowly peasant) posted disagreeing, that I have 65% GXE would hurt my credibility a lot because it's almost guaranteed that I'm just too shit at the game to know what I'm talking about.
The best quality discussion would be 2 skilled and established players that disagree with each other talking it out and responding to each other's points, and then people that got reqs can follow that discussion and ultimately decide on which one they agree more with when it comes time to cast their vote. That just doesn't happen with the current threads, though, because you (hypothetical skilled and established player) get a lot of wrong and honestly weird responses (
1,
2). Who actually wants to post in a thread where these are the responses you get?
A qualified thread will most likely filter out most of this garbage and it's going to be a net positive to everyone: players that get reqs get better quality info to cast their vote with, players that don't get reqs can see what the arguments are, and newer posters can see what high quality discussion looks like and hopefully emulate it themselves down the line.