Moving away is easy and doesn't make you likely to be hit - it's moving closer that is dangerous, because you're making a predictable movement into the reach of the enemy.

That is kind of what the abstraction is meant to represent, actually. If you close in on melee range or allow yourself to be closed in on, then you pay the penalty of being subject to OA. Close = bad. (But you pay later).

If you're in melee range and decide to attack and decide to attack, thereby putting you in range of the enemy as you lunge forward, they will now get a chance to attack you no matter what. Close = bad.

If you elect not to attack and expose yourself, you can instead disengage specifically because you chose not to recklessly attack. Far = good.