3000 domains, or 3000 links.
3000 domains are definitely aggressive. 3000 links can happen just by adding links to the footer of a site, sometimes (or a forum signature).
That said, I've never REALLY understood negative SEO campaigns - they nearly always have some form of positive impact until it gets out of control and then turns negative (from what I read), but I've never seen an SEO campaign really go negative with any of our clients. We've had people buy crappy backlinks and point to our clients, but for the most part, they give a slight boost until they fall off.
Granted, I'm not dealing with massive sites either!
One story I will share was back in the 2010-2012 time frame, I think, I ran a web hosting company. A client ran a massive web hosting forum, and as a thank you, he added our site in the footer. Overnight, we received 100,000+ links, and our site was removed from organic listings. It took time to track down what happened, but once removed, after 3 weeks, we reappeared. I know people say the sandbox doesn't exist, but the ulcers I received tell a different story

Serious concerns about the future of the business when not listed in Google.