Your premise seems to ignore that maintaining several versions, even with numerous highly dependent variations, is something that was
the norm in the software industry until relatively recently. Microsoft famously managed it with Windows for a long time until they lost the plot. I've run Debian systems for many years and never had unattended-updates break a box.
The trouble with today's highly connected world is that it has bred a culture of shipping software that isn't really production quality, on the basis that it can be fixed (or not) later and that's sufficient. This leads to arguments like your final paragraph: you (the developer) would obviously prefer to only maintain the latest and greatest of what you do, but stated without taking into account the consequences of that policy for your users/customers.
While I have a lot of sympathy for your desire, as a developer myself, I think you can only justify that sort of position if your previous releases are sufficiently good that they don't need maintenance. Otherwise, if you have customers paying for one thing, and that thing is defective, and you then want to use those defects as leverage to push your customers to something that is not what they paid for, then I think you're on very shaky ground. There are a lot of ethical, economic and legal issues raised by that sort of business strategy.