Garthanos
Arcadian Knight
I think of course why does the fighter exist if the best defender / ally protector will always be a mixed class caster? Because that is what we have in 5e.I don't even understand the question. Are you asking the point of spells like Jump in general? Are you asking what the point of having illusionists and casters able to cast fireball is if fighters get bigger tricks? Or are you asking why, if a 12th level fighter can clap their hands like the Hulk for a localised shockwave the first level wizard spell Thunderwave exists?
The distinction being ... not about individual minor thing.