Seems to be its only an issue if you are swapping phones constantly like this guy is. That said it does seem dumb to have the only way to transfer being in a phone call which obviously takes a shit while you are on the phone.
At least Apply seems to have it sorted out, going apple to apple of course. Im really not sold on esims yet. I like the ability to just pull the sim and slot it into another phone rather than fucking about like this guy is talking about.