No local access and/or physical control => don't buy it.
No exceptions.
Are there any thermostats like that? The only mass market product like that that I know of like is Philips Hue lights (their base stations have a local REST API, or at least they did last time I really used them).
My "don't buy it" threshold is unnecessarily cloud-only features or mandatory cloud integration. I should be able to take full advantage of the product's features without that extra dependency.
Its not exactly hard finding such devices these days. Often they require a cloud connection for only the initial setup.
Nest and co was totally out of question for me because of the forced cloud.
A couple days after I sign up for the account and now I am receiving all sorts of spam. You just can’t win against greed.
(I mean, I get the point, and I agree, but I don't like people assuming they know better than everybody else what kind of compromises make sense for them)