I agree insofar as I think the problem can be most directly attributed to companies desperate to appear as "woke" as possible while avoiding making any substantive changes to how they impact the world politically. Starbreaker's got a point, too—this isn't the primary reason to avoid a service like GitHub, anyway.
I don't disagree with what you say, but I hope people here don't make the error of pinning this on people with grievances in the domain of race or gender or anything else. Just use Occam's Razor. What's more likely? That this many people are actually so petulant, shallow, irrational, and overwhelmingly enraged at the slightest transgression? Or that their concerns are being taken advantage of for a marketing ploy, by a select few internet users who want attention?
It really seems to me as though this "cancel culture" stuff is more or less just corporations desperately attempting to appeal to mostly apolitical liberals who want a pat on the back for being "good people". Think of Twitter, for example. Their whole service functions on the basis of trends and engagement, so when as few as, say, 20 people get a bee in their bonnet and decide to fuck somebody up, Twitter supports this. A hashtag goes viral; people use it either because it makes them feel like a better person, or they're following the trend, or both; news outlets pick up the story; and the people to whom this news is broadcasted become confused or frustrated. But none of this means it's actually news-worthy, right? And there's no guarantee whatsoever that it reflects a significant number of people's political beliefs. It's preferable for media (whether social or mainstream) to deal with the frivolous over the serious. The latter would require them to make nuanced and disinterested inquiry and commentary, which hasn't been their modus operandi for as long as I can remember!
People on the ground just don't care about Master and Main on GitHub. They really don't. I move in some very political circles and I've never heard anyone express a concern even remotely like it. There's a lot of things these companies do that no one asked for, they just want to look progressive. It's a social currency largely of their own creation, after all. But those working to build a more just world almost always want impactful material changes, not this gutless shifting and shuffling of window-dressing on corporate products.