Because half-assing the implementation is the way to go
Let's deliver a broken version of accessibility in 10 minutes, that's much better.
No, simply adding "colour filters" isn't a fix either, and if that was the fix then a game wouldn't even need to do that, there are plenty of apps that can already do that, a game doesn't need to do anything for that (similar to how your screen warmth can change when it becomes night), reshade as an example of something that can do just that.
But thinking about the problem is ofcourse too hard, it's easier to whine about it and act like you know how simple it is. But when we implement accessibly we do think about it, because people with accessibility issues deserve to get something that actually helps rather than the "10 minute solution"
"we purposefully make it terrible, because we know it's actually better" is near to conspiracy theory level thinking.
The internal models they are working on might be better, but they are definitely not making their actual product that's publicly available right now shittier. It's exactly the thing they released, and this is its current limitations.
This has always been the type of output it would give you, we even gave it a term really early on, hallucinations. The only thing that has changed is that the novelty has worn off so you are now paying a bit more attention to it, it's not a shittier product, you're just not enthralled by it anymore.