Unfortunately, this is the way of things in the world. If you think it's ceaseless and annoying with Apple, Android will drive you stark raving mad. Every other week I have to talk my father down from his frustration and annoyance with yet another "oh it changed again" moment.
Apple really is the most consistent - that's why they do so well.
At the risk of turning this political, I sometimes suspect the moving-target nature of smartphone UIs is one of the very few ways GenXers and Millenials are subtly getting our revenge on Boomers.
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In this modern world, that's not stability, that's abandonment - I guarantee you, for example, you'll never see an update to fix security holes like the recently disclosed Meltdown/Spectre duo. My Galaxy Note 4 is in the same sort of never-never-land, and that drives me up a wall because I have yet to find a reasonable replacement (the Note 8 was SO CLOSE, but then they totally screwed up the S-View cover to the point that it's basically useless).
Google's working on rearchitecting Android so that security fixes aren't as strictly tied to feature updates anymore, but that won't be done for some time yet, and in the meantime, changes continue.