Yeah, because it was obviously meant as a quick overview, not an indepth essay.
To give some insight where those classes fill the fantasy of the heavy armored fighter archetype that can sustain a lot of damage but isn't exactly agile, in comparison to the rogue / assassin archetype that favors mobility and control over defense.
Has it ever occured to you that Plate are already slow but aren't tanky in comparison to rogues?
Could that be just a possibility?
Like seriously, read over my post, i said "slow but tanky", not "delete the mobility they have".