Pretty much this. If I want a new SIM, I have to go the provider's store, show my ID and then they will send me a text message with a code. If I have a working phone with that number I can obviously enter the code immediately in the store to unlock the SIM to be programmed to my number and can then immediately activate and use that SIM.
If I do not have a working phone with that number, the text is still sent and I have to wait 24 hours before corporate will make the SIM and send it to my registered home address. Of course if someone else tries to get a SIM for my number, they'll need an ID that matches mine for the computer to accept it and they'll need that text or a way to intercept or redirect my mail.
That's a lot of work for something that I'm liable to notice and put an end to as soon as you try to use it.