Hi, I'm completely new to home automation, but fairly tech savvy in general. I've just been bought a Google home, which has prompted me to start looking into home automation, starting with light switches. Reading around, there's a ton of different systems, each of which requires their own hub. That brings two issues. One is that, as I build up the automated home, I don't want to be tied to one vendor, but I also don't want to have millions of different hubs. The second is that we've got a large old house, with thick walls. We've had to use 3 wireless APs just to get WiFi coverage, so I also don't want to have to buy 3 of every hub.

So, initial questions:

Is the range of these hubs better than WiFi?

I know there are vendor agnostic hubs such as Smartthings or openhab. Do the switches connect directly to these, or do you still need the vendor hubs as well?

Some devices seem to just connect over WiFi. This seems far more sensible, but they're in the minority. Why don't more connect directly over WiFi?