There could be two dates in information, one for download links one for page updates and for that list the download date change date could be used. An updated description is not an updated game. And I would bet that this itch app does not update games based on updated pages. (I do not use that app, this is a guess)
But yeah, this could be exploited even with the uploaded files. Just change a small file every day.
A updated page at least tells users, that the dev still interacts with itch.