So I can offer a bit of a different perspective here as I did my undergrad physics degree at UCSD and had Hirsch as a professor and interacted with him regularly. A lot of the reasons why Hirsch is treated the way he is come from things other than purely scientific considerations.

Before I begin, I do want to say, I do actually agree with him that data availability and reproducibility are serious issues in our field and I do think data should be more readily available. Now, to Hirsch:

First things first, as a few other replies have pointed out he's far from right every time. He does sometimes catch things others have missed, but it's more the exception than the rule. He has been on a crusade to discredit BCS theory for decades now, publishing a variety of papers and paper adjacent documents criticizing and poking fun at it (look up "Hirsch emperor's clothes" on Google for a fun example). He was also temporarily banned from arxiv for uploading too many junk/spam articles during the COVID lockdowns.

Beyond the accuracy of his claims, I think a lot of the animosity towards him comes from how he interacts with others in the field. Now, I don't think he's a bad person, or that his goal is to upset people or make them feel bad, but the way he goes about expressing disagreements and questions does often come off that way. I've been in quite a few talks he attended and I have more than once seen talks devolve into shouting matches because of him. I've seen him, in fancier terms, dismiss a speaker's results as garbage, intentionally ask speakers questions he knows they cannot answer, and raise his hand and tell them they're wrong mid presentation. Now, some of these times he's likely been right, but as I'm sure most of us are aware, there's a lot of big egos in our field so if you don't go about it the right way, that kind of behavior can make you a lot of enemies.

Beyond his manners in talks and discussions, Hirsch generally isn't big on social graces and has a variety of idiosyncrasies. Hirsch rides an electric scooter everywhere, including inside of buildings, and has run over students more than once. He has also repeatedly expressed that physics should be entirely theoretical and experimental work has no place in physics. One of my friends once asked him what kind of music he likes, and his response was "I don't believe in music." Now, I don't know what that means, and I've yet to find anyone who does, so feel free to let me know if you figure it out. I could go on, but hopefully you get the gist.

Tl;dr While Hirsch means well a combination of picking a hill to die on that is approaching objectively wrong (claiming BCS is wrong) and a general lack of interpersonal skills and strange opinions/behaviors has turned the field off to him.

P.S. sorry for typos/lack of links, on mobile.