In theory you are correct but realistically you will upgrade.
The difference is without subscription, I can be pretty sure the next major version will benefit me.
With subscription,the only thing certain is that the seller wants to do as little as possible to keep taking my money. This tends to result on product updates that benefit them.
Nope, we used to just stay on the version we bought on plenty of software, because it worked fine for our needs.
This is betraying a way of thinking that suggests what's normal now is the way it's always been.
Given "there was a time that subscriptions for software were virtually unheard of", it's safe to assume we're talking about more than a couple of years ago. To talk as if most users always used to upgrade, suggests you might be young enough not to remember the software industry before a decade or two ago.
In general, users very much didn't upgrade. That's exactly why the industry forced subscriptions on us. They weren't getting income anymore, when the older version of their software did the job perfectly well.