I think its cos he's found success without being technically "good" at the instrument. He's become massive off a kinda garage band sound and relatively sloppy live work, and dudes who are more technical proficient are probably a bit bitter.

But then I haven't heard of much hate on Jack White really. I've heard negative comments about his playing but usually his songwriting is well received.

At a certain point some guitarist who acquire a lot of skill start thinking about music like it's figure skating and difficulty becomes the only standard they care about. Guitarists love Joe Satriani and Steve Vai and no one else does. White is the opposite side of that spectrum.

I wasn’t aware of other guitarists hating on him. He did a show not that long ago where he jammed with The Edge and (I think) Jimmy Page and they all seemed to get along just fine.

In not familiar with many people who genuinely hate Jack White. He's never claimed to be a stellar guitarist and a lot of his career was built on this "I'm doing this with cheap gear and I'm not amazing but I'm still making great music and so can you!" vibe which was really awesome and inspirational for a ton of new players.

I will say that I understand when he gets criticism for performances that just come across as trying too hard to be different. His Star Spangled Banner for example. Not that I personally think you have to "sing it straight" as many would say, I'm all for experimentation.... but I'm not sure I "get" what he was going for.

Creativity vs Theory. Jack isn’t technical by any means but does some creative stuff. Other guitarists dedicate their lives to theory and could run scales around him, but might not necessarily be more creative. I think there’s room for both, but some folks might disagree.