I don't see that doorbell cameras are inherently bad, the problem is they are not under your control or storing data from them locally (or not storing it).
Instead just like the insanity that no matter what country you are in, your gmail is stored and read in the USA, so it is that no matter where you are the data from the cameras are also under USA (or China depending on the model) control.
Everything in your life like that is at risk of being locked out any time.