This does not fix the issue.
Implementing something like a subscription or methods to do that on a game page would. In those cases. Currently there is none. Many games are on patreon and there is a huge incentive to offer snapshots as a separate release, as there are actually people that would pay via itch, but would not pay via patreon.
Also, itch could easily display a message to that effect to the creators that do try to delete their projects and of course this is trivial to automatically detect.
And of course, this does not adress projects that were removed for other reasons. The user just does not know. They get stealth removed. And leaves a collection inflated, and sooner or later people notize, why they have 10 items on their collection, but only 9 thumbnails.