Because they make it easy and do a few cool things.
“Do you want a mic in your home that can record everything you say and do and send that data off to wherever the company chooses?”
“No of course not.”
“What about of it will also turn your lights on and off and play despacito on demand?”
“You son of a bitch, sign me up”.
The wise thing is to not offer perpetual licenses in the first place. You can’t predict the state of your business in 10 years let alone beyond that. Why make commitments that? Marketing of course. So if they’re going to raise capital that way (by one-time revenue from sales of perpetual licenses) then they can’t just decide that perpetual doesn’t mean perpetual anymore. All in all this will come down to a legal duel between expensive legal teams.