I see this often used, but I don't think it's fully true. Many people who made their opinions on the song known did it while it was still climbing the charts. Many who had opinions about not liking AF also stuck to those opinions when it started to hit.
I also think songs like The Feels, I Can't Stop Me, Feel Special etc did bad in Korea but are much loved by the fandom. People also trashed M&M on release day when it had 700k UL's and nearly 300k sales. Same with say Midzy, have you seen much negativity toward Loco? We love that song and it's arguably one of the least successful...lack of success doesn't mean everyone is going to call a song shit.
I think it's very unfair to minimize legitimate criticism as essentially being a chart stan. I think the song is boring and made that clear almost as soon as it came out after a few listens. If this was to climb the charts and get PAK's it would still be broing and taken off my playlist.
Fully agree though!