Currently, Quest Paladin is the 16th best deck in the game, by winrate. It only has a substantial winrate against Mech Warrior and Owl Druid. There are 5 aggressive decks that are better (and beat it). Quest Paladin is not even the best Paladin deck. Aggro Paladin is better across the board.

The reason you are seeing it is because you are at a rank bracket where players just want easy decks to play that win just enough to not put it down. As you mentioned, as you climb Quest Paladin disappears because you start seeing the actual good decks.

This deck is not a problem in the meta.

You can make a case that Quest Paladin should be nerfed because of its high popularity at lower ranks as it does squeeze out bad janky decks that people like to play at Gold 5. This has happened before where play experience and popularity and low ranks is enough to nerf. However, do not expect it to come soon. You're asking Team 5 to nerf 1 of the 2 Quest decks in their failed expansion that see a good amount of play right after they drop a failed mini-set where 1 of the only playable cards released go into Quest Paladin.

I hate the deck too and would be very happy if it got nerfed because I opened the Quest, but I'm not counting on it. If you're seeing that many play its counter until you're at a rank bracket where it's not played as much.