Most annoying and least reportable form of greifing: Looking some1 up to ban their champ

So you might like or play less common champion picks. Maybe you had a few bad games in your recenthistory with a champion. I've been seeing more and more cases where a team mate will ban the last champion you played because you lost games with it or something. And if you're wondering how one can tell they're doing this, when you like a champion that iis never banned or is not played commonly, usually because they're very specialized or just not performing the best in the meta at a given time, you played it in your last game (or within a few games), and it gets banned.

I recently had an experience where I got into champion select (3v3 ranked) after playing Asol in my last game which we lost because of a leaver (no conflict, they just left without warning); I greeted, said Let's have a good game guys! my last one wasn't so hot". a short time passes, and then one of them bans asol (which is rarely picked in 3v3, much less banned), I asked them why they did that, they rwouldnt answer and branded me toxic because they didn't like the only thing I said, apparently. I ended up dodging because I didn't want to play with people that would ban a teammate's possible pick (even though I wasn't intending to play it that game).

Did I do something terribly wrong here? Can you report someone for champ select issues (if the game is played)?

I see this on a regular basis, uncommon champs getting banned because a team mate had multiple games with that champ in their recent history. Is there no way to discourage this?