You can activate an EE eSim overseas, I did it when I upgraded my 12PM to a 13PM while in the US, they either emailed me a new QR code or I did it through their app. I did the same when I switched from EE to Sky last June signed up to Sky and installed a brand new eSim while still in the US and once it was installed then ported my number across, never actually connected to the O2/Sky network until 6 months after I first signed up when I landed back in London on Christmas Eve.
But in the first example you would have still have had your old working phone. If you scour the EE Community Forums the consensus seems to be that with a dead/stolen phone you're screwed until you return. Of course if a phone's lost or stolen overseas, you've got a problem irrespective of SIM type, but with a broken phone, a Physical SIM is out from the old and into the new.
At the time of my XS Max's death (Summer of 2020) I took it to the Apple Store in Meadowhall, who told me that they would replace it under UK Consumer Rights Law. He wanted to do it there and then but, it flagged up for an inspection, so I was given a loan phone, an iPhone 8 to be exact. I then had to go to the EE Store and obtain the replacement eSIM. Several days later, I was summoned back to the Apple Store to return the iPhone 8 & receive the replacement XS Max. Back to the EE Store for another eSIM as this was pre eSIM Quick Transfer days.
As I've never been with Sky or O2 (well not since 2003) I've no idea what their practices are, though I'm aware that some carriers do indeed make it as simple as you say.
What I do know is that in the event of a lost/stolen/dead phone, with a Thai DTAC eSIM, it requires a visit to one of their service centres - no ifs or buts. Knowing Thailand like I do, I doubt that will change any time soon, especially for foreigners.
I'm not anti eSIM & I couldn't wait to get my hands on the dual SIM XS Max, as I was fed up of carrying two Max size iPhone's around with me. When my Wife & I went to the EE Store to convert them I think we were only the 3rd & 4th customers to ask foe them. The assistant had to ask us to wait for her colleague returning from his lunch break as she wasn't sure on how to do it. It's obviously moved on a lot since then, but some network carriers are still making it difficult one way or another.
It's also worth remembering that some networks still don't offer eSIM e.g. Lebara, though I understand it's coming. So anyone on Lebara is not going to be ordering a launch day iPhone Air.