My suggestion: Why not merely create a thread. Here, on the Discord site, wherever. Let people publicly post, along with one short sentence about why I am blacklisting that person(s).
For example (these are made up)
Timmy123456: Played each turn after 4 minutes, and posted in chat it was intentional.
biglion123456: Called me, in chat, a n***r, f**k you, and repeatedly said my win was only due to luck
MrThirdExample: Kept complaining about his bad draws.
So, you all could see what I wrote about the three people I had personally blacklisted. Everyone else might want to also blacklist Timmy. [ugh]. Many people might want to blacklist BigLion, while other people might not care at all about profanity. And maybe no one but me would block the third guy . . . his complaining, while not optimal, seems fairly benign, after all.
Then, you could add to the list. Or, you could say, "Timmy123456 also took 4+ minutes for each turn with me," which add credibility to my claim. Or you could say, "I've played BigLion 3 times, and she never used profanity in any way." So, people could see the negative and positive reviews and make their own decisions. (Or, BigLion could post a response to me on the thread.)
In my actual game-play, I have actually been very lucky so far. A few people just disappeared mid-game without resigning . . . but this could have been due to being disconnected, or other technical glitches, so I would not ban someone based on a one-time occurrence of that. A few people remarked about how lucky I had been (in their opinion), or how unlucky they had been. No biggie--just harmless immature venting and I was happy to play additional games with them.
But I have heard of a few real horror stories, so I know the evil players are out there. A public shaming is a great first step. And if 3 unrelated people have had the same sort of dreadful game interaction with the same player, then I'd like to know about it.
Just my 2 cents. :-)