It's a fun meme but a tad overrated IMO. People have been called others sheeple, brainwshed, lemmings, zombies, etc. since forever.
The one big difference with this meme is that it's quite effectively illustrated. They've put a face to it. "NPC" also has more relevance to the younger generation and their vidya games.
It's not dumb when it's so effective.
It doesn't make sense though. Parroting the same buzzwords and talking points is something the right has been doing since before the election and now the left is starting to do it to mock them... and right is calling them out as NPCs over behavior that is meant to imitate their own. It's like when someone is impersonated by someone else in a mocking fashion and then makes fun of them for looking silly while not realizing it's imitation/mockery.