It's called civility.

You run the chances of being perhaps more easily targeted by self-righteous assholes, sacrificing for the common good you hope to also benefit from. If you appreciate that being able to separately browse between AI and non-AI works is useful, especially without particular moral judgement, and recognize this capability as socially facilitated, then the way to cultivate that behavior is to take the leap if you can yourself.

As long as people are on the lookout for AI stuff with their eyes in the red, this won't work. If you invert the mechanism and tell people hey my shit is AI, you take the wind out their sails, and directly disprove that you're some monster trying to trick or hurt them. It's easily avoided, so that narrative doesn't work anymore. Less ground for the villification to work on their part, as you can no longer be the cartoon villian they want to think you are.

Not the first platform with this feature by far either.

It's basically an honor system. The point is exactly to show that you're willing to be (somewhat) vulnerable. You can only demonstrate that you're not misusing people's trust, if there is trust to misuse. As long as AI usage is treated as betrayal, this is what remains. https://en.wikipedia.org/wiki/Honor_system