The major difference you may be overlooking is that now everything is connected and online, and as a result the software we use day-to-day needs much more active maintenance than before.
When you had a computer sitting in your home that connected to the Internet via modem for 2 hours a day, your OS or apps could be riddled with hidden bugs and holes and it didn't matter as much.
Now we are constantly operating in insecure-by-default environments, and (responsible) companies have to spend much more to monitor, improve and maintain their applications over time, as devices change, underlying operating systems change, new threats are detected and published, etc..
When you had a computer sitting in your home that connected to the Internet via modem for 2 hours a day, your OS or apps could be riddled with hidden bugs and holes and it didn't matter as much.
Now we are constantly operating in insecure-by-default environments, and (responsible) companies have to spend much more to monitor, improve and maintain their applications over time, as devices change, underlying operating systems change, new threats are detected and published, etc..
Hence subscriptions..