There’s standardised power distribution voltages in various systems.
In the ac grid, there’s commonly a selection of (was 110v in olden daze, or even 105v), 120v, 240v, 208v, 277v, 440/480v, all in various relationships to ground. You can buy devices in these voltages on ebay, home improvment, hardware, or industrial/commercial stores anywhere. Normal home power in usa is only 120v and 240v, but i have seen apartments run at 120v and 208v, and hotels run 120v and 277v (the thru-wall hvac in each unit, yea, someone had a scheme and found a sucker).
In dc, i have seen 10v-14v, 17v-21v, 20v-28v, 44v-56v, 72v, 110v, and 160v. The 12v range is mostly common in cars, and small computer UPS systems, i have several, every computer on this desk is on a 12v 2kw UPS. Actually, the battery is kept charged at 13.6v, it’s dead at 10.8v, the solar panels put out 17v. I have used a 24v convertor, and know someone using a 48v convertor, which charges at 54.5v and is dead at ~42v. My electric car ran on 36v, i know someone who is running his at 72v. I saw a power gurney run 96v nicads internally, but it charged from the regular 120vac, and supplied 115vac with an “invertor”. I ran some CFL on 100vdc so they would not flicker or buzz. I have some router psu at 42vdc for POE devices.
My point is the ac grid has been around forever, and from necessity it’s got a limited acceptable voltage range, and a huge variety of appliances made to plug into it, even if there’s 100’s of different outlets. It’s also pretty stable when it’s working, due to low impedance, automatic voltage regulators sprinkled around, and circuit breakers.
Any dc system is going to be a headache to set up, mostly due to battery voltages wandering around, and people not installing the types of infrastructure, regulators, and protection devices normally found on the ac system. And there’s the lack of dc appliances for just about any battery voltage you can name. Can you goto Home Depot and buy a breaker panel for any dc system you want? What about a voltage booster so the little 12vdc 5amp pump 300ft down at the creek has proper voltage at all times? A regulator so the 17v solar panels don’t overvolt the system? An alarm clock? Desk lamp? Most people are not able to deal with building a tiny dc electrical system from scratch, they’d be better off buying a package deal of charger(s)-battery-convertor to power a normal 115vac grid in their home.
That’s my opinion. I am sure i am a horrible person.