crossover lost that meaning in more current era stories due to how big they are often made to be advertisement wise.
FF14 on the other hand is following more to that old style being canon but not important nor impactful to the over Main story as a whole. Just a small moment in time when two paths of different stories cross with each other and split off again on their own path once more. They may add more to the lore by expanding old lore we know but will not impact the grand scheme of things.
They did this back in Final Fantasy Mobius (RIP that FF game) as well where they made the FF game crossover canon to the other FF game stories. FF7 crossover event is when Cloud mind was still messed up in the wheel chair, FFXIII crossover event takes place after FFXIII Lightning returns right before she fully reincarnated to the new world (aka Earth), FF8 crossover event took place during the moment when Squall was lost in time and space while traveling to that spot he promised to meet Rinoa at the ending of FF8, and FF10 crossover event is even confirmed directly by the original writers of FF10 to be Tidus side of FFX-2 story (love how they brought back the laugh in HD and how they show Tidus being aware he is never called his real name during FFX).