> technically it's the same with proper RPis, where they're the only SBC board (not x86 baed) that you're guaranteed will have at least some software support after 5+ years
This isn't quite true, though it's true at the RPi's price point. For example, Toradex (disclosure: I work for Toradex) produces the colibri-imx6 system-on-module that can be turned into an SBC with a stock carrier board. It was introduced in 2014, continues to be supported today, and will continue to be supported until 2036. But that level of long-term support and maintenance costs money, and the pricing reflects that.
This is often a gilded cage. Think about it. On one hand Great, you dont have to redesign your SBC, that would take whole ~1-2 engineering man months (small simple SBC at not bureaucratic nightmare small to middle size company, obviously man hours go thru the window at big many cook orgs). On the other hand you keep shipping SLOW AS ASS SBC to your customers while Chinese competition keeps redesigning _every year_ and offers smoother UI experience with more features for less money.
This isn't quite true, though it's true at the RPi's price point. For example, Toradex (disclosure: I work for Toradex) produces the colibri-imx6 system-on-module that can be turned into an SBC with a stock carrier board. It was introduced in 2014, continues to be supported today, and will continue to be supported until 2036. But that level of long-term support and maintenance costs money, and the pricing reflects that.