My thinking was the same for years, but then I learned about Home Assistant. It's a wonderful open source package that integrates with everything. And there's a lot of options for local wired or wireless transports that keeps smart home usable without third party servers or even an internet connection.
In my setup I have some Wi-Fi connected outlets running Tasmota and some light bulbs and thermostats on Zigbee.
I can appreciate that. I have Phillips Hue setup with some lights and schedule. Having the porch and a few exterior lights come on/off makes the house feel more comfortable and is really nice when arriving at a late hour.
That is a perfectly reasonable position. Personally I consider it a hobby to tweak these things. During high volatility periods of energy price home automation can be somewhat profitable too, as it enables scheduling of the load periods to coincide with cheaper power.
Would love to see a writeup make it's way to the top 60. It sounds like a fun hobby.. I had some of the early 90s/2000s devices that could do a few things but wouldn't know where to start today.
In my setup I have some Wi-Fi connected outlets running Tasmota and some light bulbs and thermostats on Zigbee.