I work in this area and it's true that OD hasn't fared well in various studies, but there are some people who swear by it. When it comes to matters of cognition and perception, it's hard to say what does or does not actually make a difference for people, and what evidence should be accepted.
After enough people asked for an OD option in my browser extension (which is used heavily in the dyslexia, ADHD, and vision impaired communities, as well as by other readers), we decided to offer it. I know the science behind it is not stunning, but who am I to tell people that the thing they think helps them read does not actually help them read? Even if they read more slowly with OD than without (something I'm not sure is true for people who choose to use OD), it's possible that one might enjoy reading more with OD even if it doesn't improve reading speed.
I wholeheartedly agree with your point about companies wanting to check the box on accessibility by offering OD, and it's unfortunate more companies don't do more.