Ugh, I'm so sorry that happened to you. But props to you for ending the session real quick before any real damage could be done.
Nookazon is such a hit or miss for me. I've met so many amazing and wonderful users on there who price their items fairly, etc. But then I've met other ones who straight up told me that the DIYs I was offering were "basic" and that I would have to fork over 4 of my "basic" recipes PLUS a bunch of NMT, just for one of her recipes. Given, it was a Celeste DIY, but I've traded for zodiac ones with other users, and have always done a 2:1 trade, not my entire stock of recipes for a single DIY. I will say, that Nookazon has allowed me to get DIYs that you often don't see here in Nook's Cranny, but at the same time, I've had a couple unpleasant run-ins with users being unrealistic and rude.
I haven't attempted a villager traded on the site, as I have all of my dream villagers. But I would be so anxious and wary to engage, especially after hearing your story. I agree, it definitely isn't the site itself, but rather the few bad apples on the site that have tarnished its reputation for me, in that aspect of trading villagers at least