Please excuse my ignorance here, but are you saying that the board makers have no say on what chip they want to incorporate into their board? And those chips firmware are not open or at least accessible to the board makers?
Board support packages very rarely get updated and usually target a very specific kernel version.
You move off that kernel version, no BSP, no boot. sad times.
This is one reason why you don't get android phones supported past the android release shipped.
You're completely at the mercy of the SoC provider. Promises of 'n' years support are quite often quietly dropped after 18 months, when they realise all the engineers have moved to working madly to get the latest SoC's BSP out of the door.
What I'm saying is treat the board as a development harness to get your project going. If you have issues with the processor don't take it up with the board maker because they're usually just as clueless. The exception would be boards like RPi or Beagle where the designers are tight with or owned by the chipmakers themselves.
But the fundamental difference here is that most people buying SBCs are treating them as self-contained COTS compute modules.
As someone that has worked with these EVKs for decades, you never treated them as part of your final product. But with the advent of Beagle and RPI, that's where we are now.
But when you buy an RPi or Beaglebone as the core of your industrial smelter and expect support for that module comparable to, say, a module from Kontron? You're going to be disappointed.
You move off that kernel version, no BSP, no boot. sad times.
This is one reason why you don't get android phones supported past the android release shipped.
You're completely at the mercy of the SoC provider. Promises of 'n' years support are quite often quietly dropped after 18 months, when they realise all the engineers have moved to working madly to get the latest SoC's BSP out of the door.
Rinse and repeat.