99% this is probably what's happened. Aussie by default blocks incoming traffic on the usual ports (25, 80, 443, etc.) but will happily remove the block if you give their support team a call and explain why you want the block removed.
There's also an option to remove it in their app these days as well I believe. Go to Service Tests -> Port Blocking and you can disable it from there.
What would make this question more interesting is can you think of any metric where they would flip, or at least consider it. For example, all the members of Hydra (a bad example, would never make 50%, but you get the idea).
Speaking as an Apple user here with a phone that does dual SIM (one physical and one eSIM), but I currently prefer the physical SIM for my primary number and eSIM as I need it for data.
For the last 18 months I've had it the other way around (eSIM primary) and I needed a data SIM with a different provider for a weekend cause I was somewhere with bad coverage on my main provider.
Getting a prepaid eSIM was very easy, but it decoupled my main number from iMessage since the eSIM slot was now linked to a different number.
So now I'm working off the theory that since I can generally get an eSIM for any country I might visit reasonably easily (the App Store has a couple of different eSIM providers), it's better to leave the eSIM empty until I need it and rely on a physical SIM for my primary.
It's not the cheapest way to go about it, but definitely the most convenient, and doesn't rely on you having to try and obtain a SIM locally (which can be very easy to very challenging depending on what country you're visiting).
I mean sure, if you're the one applying. If they're offering they can choose whatever the hell criteria they want.
If we had the dual eSIM model in Australia this would be my setup as well, but since we still have one physical and one eSIM, having the home SIM being physical basically provides the same benefits you've described.
One could say you must seize the means of reproduction.