Optional facing rules in DMG should definitly be RAW in PHB

(Not a complaint. Just an observation/opinion)

At least the first two parts should be, not the section regarding shields. Although that is an interesting option.

The optional facing rules are

• Whenever a creature ends its move, it can change its facing. Each creature has a front arc (the direction it faces), left and right side arcs, and a near arc. A creature can also change its facing as a reaction when any other creature moves.
• A creature can normally target only creatures in its front or side arcs. It can't see into its rear arc. This means an attacker in the creature's rear arc makes attack rolls against it with advantage.

I was playing a rogue and feeling pretty weak and vulnerable in combat, unable to get sneak attack, when the party was pretty spread out in a battle. I was taking on an orog 1v1 and I was just attacking, running away, he catches up, attacks. We were just taking turns in damage like rock em sock em robots, mine not being that great without sneak. I was thinking about how in the future what else I could do to not be without sneak attack for that long again, specifically what I could do in a 1v1 situation. One great idea came to mind but felt really easy to abuse. I could just bonus action disengage, move around enemy to be at their behind, gaining advantage by being unseen and then attacking. They turn around and attack me on their turn sure, but I can dance around again, attack with advantage on mine and repeat. I could do this even when an ally is near by for me to get sneak attack but just to get advantage.

RAW without the optional facing rules means a rogue could almost always gain advantage on enemies on the ground, especially in 1v1. I understand a well played rogue should be getting advantage most the time but this feels too easy. And also too easy for a DM to have creatures use against players (especially if enemies could avoid opportunity attacks). A creature and rogue doing it against each other would look like ring around the rosie.

Actually by RAW in PHB moving from the front of to behind of a creature shouldn't actually instigate an OA at all. No need for rogue to disengage since they aren't leaving their reach at all (if you use squares/hexes and extra diagonal and then side movement). Reach in PHB is only ever defined by being within x feet (usually 5ft) of a creature with no regard for direction. For the purpose of OA every creature has 360 degree vision and swiveling torsos so they can attack creatures that pass behind them. So is a creature running away from battle attacked with advantage since their attacker is unseen or do they have 360 degree vision too?

I understand most will rule with common sense but this seems like a weird thing to leave out and literal RAW suffers for it. It would have been easy to include those two little bits into a facing subsection in combat section.