I myself am guilty as hell of this, of carrying my own remixed software, juggling patches atop upstream, and feeling like getting it upstream would be far more work and labor (and ultimately like I don't really have the confidence to assert to upstream). Meanwhile upstream is screaming their heads off everywhere that they can't take it anymore, that they are not ok. It sucks that we have such amazing power, such competency, but our scaling & social functions aren't scaling into the godlike powers that are now on tap! Alas.
If not for the success of Raspberry Pi, Broadcom would have zero SBC presence today. Like many companies chasing the high volumes and high margins, they don't see the market value in a segment like this. Thus things like poor docs and weird blobs. Raspberry Pi is open to the degree it is despite Broadcom, not because of it.
Ironically, that Broadcom tie could have caused RPi to eventually lose ground to other SBCs - because the likes of Rockchip just deliver more bang for buck in SoC dept. Broadcom doesn't seem to be investing in staying competitive in the segment. So RPi's edge is just the ecosystem being more important than raw price/performance.
For now though, that's pretty much on hold, because SBC price tags are increasingly DRAM dominated instead.