Network segmentation does nothing for the types of attacks these devices perform (e.g. content recognition for upload to their tracking servers, tracking how you navigate their UI, ad delivery). I'm not worried about them spreading worms on my network. The problem is their propensity to exfiltrate data or relay propaganda. The solution to that is a legal one, or barring that, traffic filtering.

That was my motivation for the "or" (don't allow it on your network, or put it on an isolated network); it depends on your threat model and what the device could do. Some devices (like "smart" TVs) shouldn't have network access at all.