And to add to that, it's next to impossible to buy a new dumb TV without knowing the keywords you need to be looking for.
Or would it be constantly scanning and looking for an open access point, and get online once a neighbor leaves his open for a few minutes?
Aside from stupidity like that, having wifi on might be susceptible to vulnerabilities in the network stack or otherwise pollute the local airspace.
If you have a lot of devices to plug in a mixer may also be needed.