I know Adobe needs to turn a profit, but basically forcing people to subscribe rather than be able to buy perpetuals is cost prohibitive for smaller businesses. Licenses can be moved to a new computer easily if a drive goes bad, or a computer is lost/stolen, or even if an employee no longer needs the software it can be re-purposed to another. However, their licensing is also amazingly easy to maintain and understand. Yes, Bluebeam charges for upgrades to major versions (or, like you mentioned, a maintenance plan which includes unlimited support and major version upgrades). Adobe Acrobat CC version was costing around $150/year at the time.

That computer had a life expectancy of 3 years minimum. When I was purchasing Acrobat XI it was roughly $200 (I don't recall the exact amount) when bundled with a hardware purchase (new laptop). What I find an issue with the most is cost. Maybe I made my first comment when I was still a little hot headed. You've always had to buy upgrades, unless on a subscription based platform like CC or O365.

Acrobat adobe xi