I think a lot of the criticism on the series is justified. I grew up loving the books completely and it took a bit of growing up before I could look at the series more objectively. I consider Rowling to be a wonderful writer and the Harry Potter series to be one of the best in the world, but the books do have their flaws and it's okay to recognize that. I don't mind anyone pointing out things the books are lacking and I'm always happy to have discussions about it. To me however, even knowing the books' flaws doesn't really matter to me, but they don't really make me love the books any less. The good things are so great and worth it that I can ignore the bad things.

One of the things I like about reddit (despite all the bad things) is that a lot of the people here know every detail of the series, which makes discussions a lot of fun since we're not just judging characters and plots on superficial, general stuff, but take all details into account. I love that kind of stuff.

As for the things you mention, that to me leans more towards blind hate. I think a lot of those people hate the books without even having read them and a lot of others hate them because they don't seem to think that you love several series at once. Especially the kind of people who pitch Harry Potter and LotR against each other and can't stand that Harry Potter is so popular when they feel that LotR should be the only fantasy series in excistence that gets any praise. I don't like people who reject something at face value.

And yes, there are some people who have read the books and can't stand them. I feel a lot of these people don't look at the books objectively, or only look at a small part of it. Or maybe it's just me. Whatever it is, it sucks. To a certain extent, I can understand. I grew up with these books, and the characters still feel almost like real people to me. Certain decisions made in the books made me feel bitter about it and that's difficult to let go. But it makes no sense and it definitely shouldn't lead to people hating the series entirely.

The biggest thing that annoys me about people who have blind hate for anything is that there is no talking with them. I'm happy to have discussions and defend my point of view over Harry Potter or anything really, but these people don't have reasons for hating, so there is no chance of a discussion with them. They have nothing to back up their argument and they aren't willing to listen to another's point of view, they just want to hate and want others to hate as well.

Just recognize that you saying Fantastic Beasts is great, that Pottermore is fine, that there are no great plotholes, or what you do or don't consider canon is just an opinion as well. Just because you have those opinions doesn't mean everyone has. Understand that everybody looks at the series in their own way, and second, that many of us have long term attachments to these books and they mean a lot to us. That a book series can do that to us speaks of it's exellence, but also means that they have come to life in our minds and we don't look at them objectively. From your description it's clear that you don't either and that's fine. Just recognize that they are your subjective opinions and not facts.