Whether a game has cross progression simply doesn't rely on the fact that a company is big or not.
Every game is made differently, some allowing growth for new features, some not.
Note that this game was designed for a much smaller playerbase, therefore the chance of their internal systems not having been designed around cross progression is much higher.
Apart from it being a technical limitation, note that there also are legal limitations included since console companies are involved with it.
Also do note that cross progression was never promised, all we got was a rough timeframe but never an official statement that gave us an exact timeframe of which it would come.
Conditionally, if log into my world of warcraft account on a friend's computer, they give me immediate acces to all my characters and all progress, so i don't understand why i can't just unlink my EA account from one PSN and link it to another PSN
