> provide all the troubleshooting for every non-technical customer who just wants to watch Netflix but doesn't even know what a router is
People who don't even know what a router is don't buy their own equipment. Those who buy better routers don't require support for them, they call when there's a problem between the ISP and the router.
I disagree. If it is standard practice to BYOR, family or friends might give one to grandma, saying "use this, it will save you money".
I used to install satellite TV and saw this all the time. People would get old receivers from friends and family. Fortunately for me, the receivers were proprietary to that service (we don't use generic pay TV receivers in Canada) and the old ones were built like tanks. If people could have supplied any old cheap generic receiver, I probably would have had a bad time.
People who don't even know what a router is don't buy their own equipment. Those who buy better routers don't require support for them, they call when there's a problem between the ISP and the router.