DC travel as you know is a bit of an involved process, you cannot simply go to another DC world from a home aetherit like you can from worlds withen a DC. And it is impossible as of now to travel to a dc in ANOTHER region (so no NA character to jp world/dc visit without outright transferign the whole character data )

such things are an involved process, its outdated hardware and coding that only recently they have had time (and money) to do neccesary touchups to make things like world to dc possible, but even dc travel isnt very "clean"

This is why CROSS DC PF will likely be a long , long ways away where the money for hardware updating is easy, but having the time to wrangle with code thats still loaned over from the ps2 days, will be more hampering.