ya i admit some things could use more explaining or more detail to fully understand the things such as Yu wasn't approached by a blue butterfly nor met philemon before being in the velvet room unlike the rest before him with the wild card
especially since at the start of P4 it appears that Yu signed a contract before the game even began

EXACTLY , I NEVER SAW THE BLUE BUTTERFLY . Which is very important because Igor is Philemons servant .

see my point? I hope P4G explains lol

but personally i think it is possible only those with the wild card may get to sign that contract, but cannot be sure of that as I think P3 was where the contract first appeared

That is true .

But there are occasions of non wild card users being in the Velvet Room , Like in P2 , and Trinity Soul even though that isn't Canon . The purpose of the velvet room is to record Persona , which is why they go after wildcard users . So the compendium can be filled . Which is why the wildcard users each have a person to serve them .

Even though Persona 3/4 kinda stray away from where Persona 1 and 2 were . It's more dating sim vibe .

When Minato first got to the dorm in Persona 3 , Pharos had him sign the contract saying he was responsible of the choices made , of his own free will .

What's really important honestly is WHEN the person receives the velvet key .

In P2 who gets in the velvet room that doesn't have wild card?
cause don't all playable characters in it have it?

Wild Card ability doesnt exist in P2 lol . Its only an "assumption" .

Wild Card Arcana is always the fool (0)

Main chars are Sun and Moon in P2 .

Its a P3,P3:FES,P3P,P4,P4G thing . But we can only "assume" it's applied in earlier titles .

But I personally don't really apply it , because the Wild Card ability in P3/P4 is so unique with the Social Link thing it actually makes sense lol

personally i apply it in the sense they could switch between persona as they wanted/needed, which imo is the main ability of the wild card

But the wild card is the fool , which is 0 . which is limitless possibilities .

In persona 3 and 4 there are social links , which are bonds that one has to form in order to reach the ultimate persona .

This is like when you play with tarot cards , you start with the fool .

If you don't hit every part of the story with the fool card , you ultimately get a bad ending ... but if you get certain ones, or a few , it shapes different possibilities .. hmm kinda like a Wild Card .

It's possibilities are both infinite, and nothing . That is the main ability of the Wild Card .

In earlier titles, none of this . Which is why the Wild Card ability is more exclusive to P3+ .