I think this would make doing higher difficulty content less satisfying. I want to feel like I’m working my way up to strong gear.
For this reason I believe they scaled rewards to +20:
However even as a casual player let’s say you stuck to the weekly quest, conquest gear and maybe +2/+3 keys. You would still eventually end up in the high 390’s because valor upgrades go up to 392 for no rank and 395 for a rating of 600 (something you’d get anyway for doing all dungeons at +2/3). That plus the occasional heroic piece from the 4 m0 dungeon quest that comes rarely and the free primal infusion when Razageth comes to LFR means there’s a lot of sweet easy gear progression to come.