I have a "DIY" setup in my current property with Shelly modules behind light switches and everything connected to Home Assistant. It's been rock-solid for a year now and the occasional maintenance I do (updates, etc) is more out of a hobby than anything (I could air-gap the entire system onto a separate network with no internet access and forget all the security updates). Yes, it took some skill to install and configure, but that's no different from installing all the electrics (or plumbing or heating) in the first place.
A "dumb" home needs maintenance as well. Maybe people just have an unrealistic expectation from smart devices?
Most plumbing or electrical work I do will last decades. If I move, the same skills will transfer perfectly to the plumbing and wiring already installed in the new house. The last big innovation in any of that was PEX piping, which takes about five minutes to get completely competent with, and has been around for years already. People who can come out and fix any of that, if I don't feel like dealing with it, can be found anywhere and often work pretty damn cheap (unless you're getting ripped off). Almost all the maintenance is "buy part, replace part", which is fine because (in the scheme of things) most of the parts are very cheap.
Add "smart" devices to any of that, and they're instantly the most finicky and needy part of the whole system.
Alot of smart Switches will work (turn the circuit on and off) with out the controller.
Home automation, when it works, is great. If you don't have the time & skill to do it yourself, the cost of having somebody do it well for you is prohibitive unless you're in a fairly high income demographic.
And that's the problem with DIY - it's an indicator of a niche audience, not an inherent "badness".
I have this image of the Father in Zen and the Art of Motorcycle Maintenance, harping on his friends not taking care of their BMW motorcycle, letting it heat too much and not checking on it at every stop, while he's watching his Japanese model like a hawk, looking at temperature, doing mechanics on the road and so on. He's quite flustered, and condescending, saying they're not comfortable with the technology and the technological world, that they could live with a leaky faucet and not care because they can't fix it themselves. He's calling them 'romantic' and even when saying he understands how they see the world, still comes of a bit 'this is a bad state of affairs'. I used to agree with him.
I'm a tinkerer, I love gadgets, I can handle imperfect, I'm not afraid to drive my e-cargo with finicky not-fully-working brakes and 'you need to use it just right' stuff instead of bringing them to the shop or doing the big repair. I can repair but I usually also understand enough to know it can wait. That's me. Same in the house, I manage, I repair, I workaround while waiting for the thing to really break (money is tight, etc) and can live with imperfect stuff and have patience when things break down.
Then my spouse broke her knee. I had to handle my 3yo twin girls alone. The house. Twice the chores. The triple workload, while still doing productive work and trying to handle the first lockdown... The disabled partner in need of help for everything, and every hour or two every night in need of ice or pain relief. Utterly tired, sleepwalking...
My tinkering life stopped right there. I need stuff to work even when the world is falling down, I'm dead tired. No firmware update in the middle of anything, no crash while bathing the kids, no fucking reboot during a wash cycle that I needed to finish and set to dry before going to sleep at 4am to wake up at 6. You need things that absolutely work 100% of the time, just in case you're not able anymore.
So, like one other commenter said: something augmenting basically working stuff is the bare minimum. Mechanical switch is the most robust, have it working even if the system is ripped out. Electromechanical switches under your hand and display on the dashboard, in cars and not the damn crashing 17inch flat screen. No fucking software between me and the essential life support stuff. Have fun over that but make it fall back on 'what we had before' without my intervention.
After he was born, through now as a toddler: Baby Buddy ensured that I really was waking him up to feed every four hours as a newborn and helped us keep tabs on fevers vs. diaper signs, because my brain is broken. Raspberry Pi 4 is just running PiHole, with IoT gear sitting in Aspiration Cabinet. I am relearning Kubernetes and Terraform. Thank God Germany has really strong parental employee protections.
If you work with devices that adhere to some sort of common standard things are usually much easier, less gotchas, less weird hacks that depend on specific versions or intricates of some commercial product etc.
Pretty good solution.
The only downside is that they aren't available in the UK, but that's not uncommon for non-mainstream smart home products.
Ex. I used a lutron caseta smart switch with and a pico remote to add three way switching for my kitchen and dining room. Where they used to only have one inconveniently located switch.
The Shelly pro 4pm installs in the electric wiring cabinet. It speaks MQTT standard messaging across wired ethernet, but it can also integrate with Shelly's cloud thingies. It's a smart, standards based drop in replacement for ordinary "dumb" AC teleruptor/impulse relay star topology wiring.
My mil has purchased some seriously sketchy outlets off Amazon to install because she wanted to modern style but didn't want to pay the Leviton/Legrand premium from the home center duopoly.
If you're purchasing in-wall electrical, I strongly encourage you to buy a name brand from a reputable source. Also spend the extra half dollar for nylon plates that won't crack or shatter.