What they're actually trying to do is obsolete the devices faster because then they won't add new protocols or other software-only features to older devices so you have to buy a new one, or only expose features in more expensive models that the less expensive hardware would also be capable of doing. Which is all the more reason for us to not have that.
And if they were required to allow anyone to replace the firmware then you would get companies reflashing and selling them that way from the store because the free firmware has more advertisable features. There's a reason you can go to major PC OEMs and pick between Windows, Linux and "don't even install one" and the reason is that if you give customers a choice, they generally don't want their software to be made by the OEM.
This is exactly why. Obsoleting older devices keeps (in their eyes) the purchase treadmill running. Making a device that could be updated forever means never making another sale to that user (unless some physical failure happens, or the user wants a second one).
Anyhow, this is a common enough practice. Many companies that provide infrastructure type software and sell to Fortune 500 companies often have a clause whereby they deliver their software to their customers if the shut down.
And you can't wait until after they're dead to have them do something. By then they're gone or judgment proof because they're already bankrupt. Especially when you're talking about companies that aren't in the jurisdiction because you can't even make them do anything when they're already not shipping products to you anymore. It has to be from Day 1.
There was a promising design from Azure Sphere for 10 years of IoT device Linux security updates from Microsoft, even if the IoT vendor went out of business. This required a hardware design to isolate vendor userspace code from device security code, so they could be updated independently. Could be resurrected as open standard with FRAND licensing.
