I think they miss the point entirely.
It's about saying "My eSim is XXXXXXXXXXXXXX. Please can I move to your service?" Whether you do that online, via the device itself, by entering a code on a signup instruction, or buy "buying" a little card in a newsagent and following the instructions, it doesn't matter. In effect, it doesn't matter whether it's a bit of plastic, there's no need for any stupid menus (that's a rubbish argument if ever I heard one),, etc. You just need a page on a provider's website with a place to enter your eSim number, some kind of text-message verification and, bang, you've changed suppliers to any one you want in the world.
Don't forget - buying a SIM is not the end of the process. You often have to "top up" nowadays before you even start, so there's usually a need to do something beyond just buying the SIM .
In effect, this actually bypasses the need for the SIM number itself, too. All you need know is "this is my phone number" and from there you can port the phone number and eSIM to any provider you like just by asking them.
eSim is a good idea. It's not ground-breaking. But it's a good idea. Why we're all determined to rid ourselves of tiny little slots that take up next to no room and have been shrinking forever, I can't fathom. But if people want that, sure, it's nice and easy.
"Hey, Vodafone, you suck! Hey, Giffgaff! My eSim code is XXXXXXXXX, sign me up!"
"Hey, I've just landed in an airport, taken a leaflet for Spain Telecom, I ring this number, type in my eSim number, it texts me, I confirm, bang I'm online".
Why anyone would state that needs any bits of plastic, interactive menus of contracts or MVNOs or anything else, I can't imagine.