Some do, some don't. But if you want to use Alexa or Google Home or Siri to control you do need an internet connection to do the voice translate to command bit.
Personally I've gone with SmartThings (Samsung) to control the home tech and use Amazon as the voice interface. This allows me to be reasonably agnostic of vendor and interfacing standards (ZWave/Zigbee/Wifi), allows me to use a scripting language to control some aspects of automation (using Webcore app) and still use Amazon to issue voice commands to the same devices.
Kids love it, I like it, but not got full wife acceptance yet, she gets frustrated turns stuff off at the wall and then all the automation needs debugging!
Yeah, a requirement for an active internet connection would completely kill it for me, much more than the cost, so it's nice to hear that it can use local networking only. Also, as you mention, the fact that it's not very compatible with the mechanical switches seems like it would be annoying, though I suppose those can be replaced with wifi equivalents.
The bigger thing is that I just don't see huge benefits to smart lights, and potentially a lot of maintenance headache - I just don't really mind walking to the switch.
An automated blind opener that is set to slowly open automatically based on what I've set my phone alarm to that day, though, that I would pay a lot and put up with a lot of crap for.
Smart things actually requires an internet connection at times. I don't know what exactly causes it, but several times when my internet has gone out, I've been unable to control the lights.
Lots of people have switched away from smart things for this reason.
They make dimmer switches that can be controlled via Zwave/Zigbee as well. If you replace your wall switches with these instead of using bulbs that do the same thing, your automations will have no more problems of this sort.
Personally I've gone with SmartThings (Samsung) to control the home tech and use Amazon as the voice interface. This allows me to be reasonably agnostic of vendor and interfacing standards (ZWave/Zigbee/Wifi), allows me to use a scripting language to control some aspects of automation (using Webcore app) and still use Amazon to issue voice commands to the same devices.
Kids love it, I like it, but not got full wife acceptance yet, she gets frustrated turns stuff off at the wall and then all the automation needs debugging!