I don't know about policy here, but I don't see a problem with talking about your favorite itch.io games on your profile page (I would certainly be happy if anyone mentioned mine!), and also the ability to display your collections on your profile seems suited to that.
Ah, I just re-read the title, and you are right. If OP is reading this, you should be able to add other people’s games in your profile page. In fact there’s functionality to include collections, so I’m sure including other kind of information is also encouraged.
My other comment was about including that kind of information on a game’s page.
Yeah, I wasn't clear on whether we're talking about game or profile pages, also. Certainly we don't want to see people try to manipulate search results to get more views, but I'd love to see developers promote each other's work (even though I don't do enough of that myself), credit other games as inspiration, etc.