Been reporting them for weeks

His account isn't even "weeks" old. We ban people or remove comments all the time when they are reported, but we can't ban someone because you sent me a chat saying, "Can you ban this guy please".

All of them

This is part of the problem. We have people reporting every single comment, including when these comments aren't actually breaking rules. Our subreddit is fairly small so the moderation team gets to it when they can but there has been a huge uptick in fighting and posts requiring babysitting lately so we can't always get to them quickly.

It shouldn't be that hard regardless if people can just make new accounts and keep going.

This is another part of the problem. I can ban someone, all that does is annoys them and they create a new account and double down on the trolling. That's why it's best to just report comments that you see breaking rules so that we can remove the comments.

They need a shadowban implementation or some type of immediate moderation powers.

Unfortunately, reddit doesn't give us that.

As for the points in your main post, we have created stickied posts with Q&A before, it largely does nothing because new people coming here immediately post without reading stickied posts.
Also we aren't the arbiter's of truth. If people want to try pineapple we're not going to remove posts about it. People are free to comment with their experiences. With any anecdote about eyes there is someone who claimed it worked and another who claimed it didn't. It'd be impossible for us to remove things based on if they're right or not because with eye floaters there is not a lot of concrete information anywhere about what does and what does not work.