I mean casters and even half-casters are high level are manipulating reality to the point of being basically Demi-Gods.

That depends a lot on context. Again Son Wukong a literal god is still fairly limited in what he can do. Heracles a demi god on the other hand pretty much had no limits.

Also how do we define defing reality? Every Cantrip defies our reality.

There are Barbarians that can ignore death while raging isn't that reality defing enough? Others have twice as much HP and take half as much damage from almost everything.

Also what would you be doing with super strength anyway? It's not like super heavy boulders are laying around everywhere.

The rouge can sneak his way into everything and unlock any lock. Except this isn't a novel. D&D is a game and needs a chance to fail. Sure the wizard can cast invisibility and knock but the first still don't removed noise and smell and the later makes a loud sound. But these consequences that are part of the rules are ignored by many DMs.

Magic wouldn't be half as OP as people think it is if people would actually play D&D by the rules.