Most people aren't 'average in all stats with one stat maxed', though. Your character is every bit a 'mathematical equation' as the rest.
I'm speaking for characters starting with two of their most important stats near 7 and slowly building from there. That way feats like grenadier(dex6) or armor sloping(int6) or sprint(agi6) etc are always open for the player.
Just finished Depot A with a hammer-man like that and it was one of the easiest Depot runs I ever had. Two hypos, 4 bandages, 5 EMP grenades, 2 antipersonel grenades, 5 Molotovs, 1 caltrop. Zero sneaking. It made me smile because I saw it as testament of Underrail's character system flexibility.
The system is indeed flexible and I fear that all this constant talk about min-maxing is going to keep a lot of people away from investing time in the game. I could argue that the game is "easy" no matter the build as long as you know how the systems work. E.g a new player fighting a room full of bots VS a veteran player in the same room with the same crappy build. The former will probably quit the game but the later will be invisible due to knowledge(immune to bullets from a vest and immune to flashbangs from a helmet with shades).
Anyways, original question is answered.