More specific to promo cards was the fact that they introduced a whole new audience to the game it was promoting
Getting the effect on a body is always nice, however, opening up the potential for blink loops and reanimation shenanigans
Its functionally similar to Two-Headed Giant in some ways, and itll be interesting to see how some of the more collaborative cards featured in Team-Up function in that game format or even in Commander, where it might behoove you to help out an opponent to take down another
If your creature survives, you've got reach plus a body
They still need to exert and cant Quest, Sing, or use other abilities that require exertion
The second ability of Cid, Timeless Artificer also lets you ignore the "singleton" rule in formats like Commander