The hardware was evolving way faster 40 years ago and in much consequent ways than these days. Plus number of users grew exponentially. So a company spending too much efforts on software could loose its edge on the hardware side. And locking hardware would be counterproductive since as it would limit new users.

These days things are way slower and the are no exponential growth in users. Plus fast cellular networks made the speed of local hardware much less relevant. So the software became way more important and so its control.