Well yeah, even if you designed the most ergonomic thing that's ever been created, there will always be some it doesn't work for, because everybody is different.
And when you go onto a popular forum and look for people who feel the same, you will find some, even if the vast majority find it comfortable.
Reviews pretty much all said the deck is very ergonomic.
The steam deck is much wider than a normal controller, so much less of an angle is needed for a comfortable grip. There's a reason that most handhelds (Switch, Rog Ally, Lenovo Go, Wii U gamepad, etc) don't have angled grips.
I find the regular steam deck to be very comfortable for it's size and weight.