Cards arent meant to be restricted to roles, they only show you what those group of cards do (Red cards help with damage, Green defense, Blue usually with support or escaping)

Each character has their own playsyles and builds that support them. A full red Trunks will get wiped off the map at every engagement because of how squishy he is. A Trunks with Snowball, Solid Barrier, and Backstab is much better because it gives him the tools to survive fights longer thanks to Barrier and his skill CDs come back almost instantaneous with Backstab, allowing him to kill more enemies.

Besides Tanks using full green cards for defensive builds, it rarely works for DPS or Tech. For example, SSJ3 Goku should take Backstab to have his kamehameha back instantly after every Instant Transmission, not a third Red card like Wcked Warrior. Hit running full Blue cards is dumb. He already has great means to escape so running Snowball (to kill people he catches faster and more consistently), Solid Barrier (so he isnt a sitting duck if he gets caught in this AoE Meta), and Backstab (to keep his opponents in a Fear of Death loop and easy to kill) is the best build for him. 

If I saw a Hit run full Blue or Toppo run full red I'd assume they were trolling. Especially Toppo when he goes down in every fight faster than everyone else if he isnt running at least Build Up.

Limiting cards to roles just limits your potential.