https://itch.io/games/tag-unity has 100k games
https://itch.io/games/made-with-unity has 250k games
Overlap is only 50k. Which should make 300k total.
It gets more complicated for rpg maker. But my point is, that meta-infos are mixed in inconsistently with the regular tags. Someone searching Unity games will not find most of them if listening to the suggested tags. https://itch.io/tags/tools
And even with the made-with tag, about 50k will not be found. I would dislike searching twice and I think many people would not even realize that there are two tags saying the same, one a regular tag, one a meta tag, and that there is a huge lack of overlap.