They ran into the problem of: they finally made the software right and a person can buy it and have software that works. Without bugs or missing features or other problems compelling you to upgrade to a new version.
Unlike a car that wears out, the only way for them to continue to make income is with new users and there's a limited number of people who want high-end CAD CAM. There's a finite amount of growth that can occur in that industry.
So, other than packing up their bags and saying "yep, we finally finished the best CAD CAM program out there, we're done, we're going to go move on to something else now" they had to make it a subscription service or they would be toast.
I bought some software, it works for me. I don't want to buy new software. "You have to buy the new software we will go bankrupt!"
State of the art software from 2010, that cost as much as a new car, still works. I don't think I want to replace it