It’s a start for sure, a TV that’s really out to track you might well be able to circumvent these blocks, but most TVs (and indeed most tracking technologies on the web) to my understanding are not so sophisticated. For the average person who wants to enjoy some of the smart features of their TV this is a good compromise.

And I’m not sure what you mean by the router being the better place to add guardrails. What sort of guardrails can you possibly add outside of blocking internet access outright to the TV? It would be near impossible to distinguish between legitimate traffic and ad/tracking traffic without resorting to something like SNI sniffing which again can be bypassed.