CSS is just hard. For small sites, early stage startups, and personal blogs it is relatively easy. You can organize your CSS along many different axes; the "optimal" CSS structure depends on the exact size and architecture of a site at a specific point in time. This is why there was an early backlash against CSS grid systems when they started to come out, because purists saw it as diluting the semantic value of the markup, but they missed the fact that when sites grow you need an abstraction.
What Nicole Sullivan does is tackle CSS nightmares at their worst: in massive sites like Facebook. In this kind of environment 90% of what you read about CSS best practices is garbage because 90% of people writing about CSS aren't working on sites this big. Actually to get a lot of exposure and become a CSS guru you have to work on a breadth of sites, probably in some kind of consulting or agency context, which tends to be orthogonal to long-term maintenance concerns.
I've heard Nicole speak, and I've also maintained 10k+ LOC of CSS before, and I can attest that she really really knows what she's talking about, and I believe in OOCSS for massive sites. For most sites though, it's probably unnecessary and overkill. The other tricky thing is that you can't do OOCSS effectively until your design is somewhat established and the visual language is clear. Therefore I agree CSSLint is much less useful in general than JSLint, but it's a tool I'd keep in your back pocket for sure.