Earlier quoted context omitted.
In my jurisdiction, consumer device must have "reasonable lifetime" by law. This lifetime of course is not to be determined by the manufacturer, but by the courts in the event of a disagreement. Ten years is bit long, but it's not absurd to think (i.e. reasonable) it should work ten years after the time of purchase even if the technology becomes obsolete.
Nobody would sell consumer electronics in your jurisdiction if they thought it were a remote possibility that courts would endorse "Purchase date + 10 years" or even "First sale date + 10 years" for software updates . An original iPad isn't even 10 years old and is many years past being able to run an iOS version that receives security updates. A 10 year old MacBook Pro is a few years beyond having a supported OS wit…
However consumer goods must be fit for purpose for a reasonable time. The case of the insecure router after 5-10 years was probably not brought to court, but I hope the court would agree that it isn't fit for purpose if insecure..
If you are really interested, you can read on the law here (my jurisdiction is Quebec, Canada) : https://www.opc.gouv.qc.ca/en/consumer/good-service/goods/sm...
Fortunately, we don't have to care what manufacturers think is absurd or not; it's been decided for them.