Because exactly the same features and systems that make things appear realistic, will usually break the game if used in a gamey way.
First I brofisted but then thought about it and...not really.
What really breaks the game is the systems tied to stealing, looting and fighting are only half-way to where they should be. They're undercooked.
You get way too rich way too soon because the "stolen" tag disappears way too fast. It probably shouldn't disappear at all (stolen meat tag definitely shouldn't disappear by roasting the meat). The only way to sell stolen shit should be the fencers and they should have a limited amount of purchasing power (both limited money and the willingness to buy big expensive shit). Also stealing gets too easy very quick, people are too oblivious to you rummaging through their houses.
Plus the preorder gear is way too OP for how early in the game you can get it. But that's an RPG tradition since time immemorial, preorder shit is always OP, always out of place and you should never buy it.
And lastly your late game attack/defense scales very poorly. You shouldn't be able to two-hit even elite mobs. Also masterstrokes are too OP and combos useless.
All that is not because people try to break the game, the problem is the game is just too easy to break. But Warhorse don't have to change their realism approach whatsoever, all they need to do to fix it is just tighten up some loose screws, that's it.