I'm going to say a few things here, and I don't care if you think one contradicts the others.
One. Rejecting an idea because of who proposes it is stupid. Formally stupid, in fact; that's tantamount to what you call an ad hominem attack, which is a logical fallacy, which is a fancy way of saying it's a really poor and unethical way to argue, which is a polite way of calling people who use it stupid.
Two. Individualism is great, yeah, I get it. I'm an individualist and a nonconformist. However, being different for the sake of being different is also stupid. The whole point of individualism, even when applied to a community, is to ensure that one can be healthy by being oneself, not to show how fancy and special you are.
Three. Tossing insults around instead of actual discussion as I've seen happen in every goddamn thread about competitive battling on this forum is also stupid. Responding to "I think wifi clause is good" with "lol that argument sucks so fuck you" is toxic, and I know toxic. This also applies to suggestions.
tl;dr stop bitching at each other and have a civil discussion so I don't have to start cursing on this forum any more
With that out of the way, I support the idea of making wifi clause the default, and having a separate tier for no preview. People who are that bent about wifi clause can use the no-preview tier. Team preview is more competitive in my humble opinion due to the elimination of gimmicks and it tests each player more. Limiting the information available to the player when they have no way to find said information before it sweeps half of their team a la Genesect makes for a very frustrating and very uncompetitive experience. Without preview, you could feasibly pull off well-known gimmicks like FEAR Rattata and Aron, and it makes it basically impossible to run more niche pokes such as Shedinja because you can't really determine if there's a threat to them without burning through valuable HP and turns scouting them. This isn't a RTS where scouting is simple and easy; every single member of your team needs to do something important, and each is invaluable.