There are genuine instances where an OS upgrade will cause issues, as mentioned. But is it deliberate? Gonna be hard to say, especially when you have to define what aspect was deliberate*, then have documents from the various planning phases and/or easily-navigable source code for each device across a variety of OS releases to give proof of intent.
I know I'm susceptible to placebo/nocebo effects and try to work around them as best I can, so I don't consider this a major concern for myself. I might be open to buying a new device if it becomes utterly unusable, but I also know my general upgrade cycle well enough to know when I am causing it to be unusable because I just do too much. [Yes, that is a thing for me.**]
*: slowing the device down for the express purpose of selling new devices, or simply pushing out an update with no regard for performance (expecting things to be fine) for the sake of end user experience and brand reputation.
**: I'm pretty sure I run across physical hardware limitations more readily than most people, and I also run across physical hardware degradation from time to time, but I can only wonder whether I use devices for a period longer than intended by the manufacturers.