SFF PCs in HP, Dell, and other office computers have been using 12v only PSUs for a while now.
In my personal experience over the last 5 years, we have had maybe five PSU or MB failures out of thousands of deployed PCs. The pros (size, cost, efficiency, complexity) outweigh the cons given how extremely few things use not-12v.
Most laptops and micro desktops use 19.5v. Type-C charging is also 19.5v in the 100w spec. The batteries in the laptops I support range from 7.4v to 11.4v;
Laptop Model Battery Type Watt Hours Voltage Dell Part Number
Latitude 5*50 G5M10 51Wh 7.4v #451-BBLN
Latitude 5*70 NGGX5 47Wh 11.4v #451-BBUJ
Latitude 5*70 6MT4T 62Wh 7.6v #451-BBTW
Latitude 5*80 GJKNX 68Wh 7.6v #451-BBZG
Latitude 5*90 GJKNX 68Wh 7.6v #451-BBZG
Latitude 7280 F3G33 45Wh 11.1v #451-BBFX
Latitude 7270 J60J5 55Wh 7.6v #451-BBSY
Latitude 7280 F3YGT 60Wh 7.6v #451-BBYE
Dell's office SFF PCs have been using these PSUs since the 20-series, so about 6 years now. The 10-series before it, which had a standard 24-pin, was the one with all the failures. HP has been on 12v-only for a while as well.
How many MB failures do you get on a regular basis? They are really not all that common, and even when there is a swap it's like 5 minutes of work. They do a good job of making these things repairable.