Since WSJ is paywalled (and since it looks like an opinion piece) I had to go searching for other articles.
The best I can make out is that the museum's unpaid docents program wasn't representative and mostly consisted of older white individuals who were more financially well off. Being a docent required a significant time increase for the initial and continuing training and education that one docent likened to a full-time job.
Previous efforts to increase diversity through recruiting efforts failed to make a meaningful impact. So, the museum decided to end its volunteer program and instead go with part-time paid docents. However, being that they are part-time they won't have the same level of training as the current docents.
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Jake's - and conservative sites - headlines are obviously rage-bait and the situation is more nuanced than that. Representation in the art world is an issue and it makes sense to want a representative group being the ones explaining and educating the visitors. It also makes sense that people who aren't financially well off don't have the ability to devote significant time to a volunteer position. And, we know how closely race and wealth are associated. So, getting rid of the volunteer program and replacing it with a paid program makes sense.
All that said, I'm not loving the solution and would have one that did effectively increase diversity while still allowing the people who have invested so much time to keep showing people around the museum.