That would only solve your browsing for assets issue, if there were an agreed upon and enforced tag that indicates the usage of "AI". And there would be needed a definition how much AI is considered AI.
Is it even mandatory to disclose the usage of AI? Is there anything in the tos or in the quality guidelines?
It kinda is! https://itch.io/docs/creators/quality-guidelines#avoid-uploading-excessive-amoun...
If your project involves automatic or AI generation, make sure it’s clearly stated in your project description
But there is no rule about tagging it in any way. So you will still have to read the description. And for assets, the number for projects is usually a good hint, if AI generated or manually made.
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Oh, and there is no refusal to implement the feature. There is just no official statement about such features. It might come, it might not. My guess is, that it depends on how cheap it is to implement it, and that a working feature would be hard to impose on the current system. For multiple tags. The old "inofficial" feature to filter out one tag never got an ui button. I made one, if you use Chrome. I also made another helper, that will let you ignore asset developers that you know to make AI assets. Or you can use a user style addon to filter them out.