“I’m across an ocean from any of my network’s stores and need to activate a different phone on my regular network and number right now, on the side of the road,

“I’m across an ocean from any of my network’s stores and need to activate a different phone on my regular network and number right now, on the side of the road, without WiFi or a computer or a different, working phone already on my account” is to me the most obvious case where eSIM is weak. And having been in that situation before eSIMs, it was really easy - remove SIM, put in backup phone, use. Not so much now.