I mean I remember when this thread was posted, it was at a kinda weird time for NA NW. Their scene didn't really start from the ground up like EU did. There were regiments in EU who would bring large groups of NA's, like the OG 51st did. When bluefang hosting etc. started supporting NW thats when the big regiments in NA started, but the thing I remember the most about 2013 is literally everyone complaining about how shitty the servers and competition were. Come to think of it, it took them a good while to pick up tournament formats etc. that EU had done. Pair that with losing interest I can kinda understand why they felt this way 7 years ago.
Back then you had plenty of regiments who were all pulling in big numbers but suddenly started to shrink down. Honestly I would just put it forward to that honeymoon period. DLC had been out for 2 years and people started to lose interest. That goes for both EU and NA obviously.