What was screwed up about the NA ranks?

NA is (or at least was when I played) the most populated and visible regional zone, and attracts a lot of players attempting various kinds of rank manipulation. On the one hand you have smurfing, which is the practice of a relatively high skill player using a an account with relatively low rank so that they can dominate lower ranked players. On the other side you have boosting, which is a relatively high skill player ranking up new accounts for later sale.

In practice this means at lower ranks, it was not at all uncommon to be matched with players with similar rank but vastly better skills.

This was my experience too years ago when I played CSGO. The difficulty at higher ranks (up to a certain point) felt significantly easier than the lower ranks. Getting out of the silver and gold ranks (can't remember the exact names) was a hellish grind with lots of matches that ended in one sided stomps with one or two guys on the other team racking up some insane k/d. Past that was smooth sailing for a long long way.

At the time, there were no people of very high ranks. I also queued office only which didn't help.

It's basically impossible to keep one's rank at Supreme if you only play against Gold Nova or so due to the way the rating system works.

Yep - same story here with Nuke (the old one, but then it happened again on the new one too). Got to global and it was a ghost town save for the same 5 man we ran into every night.