Honestly, since it's well-established that MJ got a ton of plastic surgeries on his face because he was unhappy with the way he looked, I don't see why it's hard to believe he bleached his skin because he wanted to be lighter. He was bullied by his father for having dark skin and iirc, he envied LaToya for having light skin. That's not to say he didn't have vitiligo, but there's a chance he got it as a result of bleaching his skin too much. In a lot of communities, particularly the black community, light skin is coveted and many darker-skinned people take stuff like skin-lightening creams to gain lighter skin.
MJ's skin didn't start to look white until 1992, anyway. During the
Bad and early
Dangerous era, he could still pass as a lighter-skinned black or mixed-race person, but he used makeup to appear lighter than he really was like in Captain EO and the Bad music video. The cover art for
Bad was also photoshopped to make himself look lighter. In a telephone conversation, he said of the cover, "That was all airbrushed. I don't [actually] look that perfect". So, it seems to me that the Bad cover was MJ's ideal vision for how he wanted himself to look. He went out of his way to lighten his skin to achieve that look and got vitiligo as a result, so he had to make himself lighter than he wanted for an even skin tone.
Even this site thought that was silly when they interviewed him:
https://www.mjjcommunity.com/threads/exclusive-q-a-with-jermaine-jackson.200478