I've seen large companies pay six figures to stand up a microsite, the kind of thing that one person could easily put together in a few weeks.
The catch is that you don't necessarily have a few weeks, you have a few days to go from concept exploration to go-live. It really becomes more about project management than web development in these instances, having a network who you can turn to quickly when you need more hands on deck.
And though I hate the phrase "full-stack" because it means so many things that it sometimes seems like it means nothing, they do really expect a well-rounded technologist.
Those people are invaluable. Someone who can write a little HTML and CSS and maybe stand up WordPress? I'm sure there are jobs for that, but I don't have any need to hire them as a freelancer because I expect everyone on our staff to have those abilities.
That said, doing freelance web dev is _exactly_ how I got my foot in the door with the job I have now. But it paid squat for the time I was doing it, and I hated it because my time ended up being 50%+ of the time running the business side of things instead of building website, which is the part I actually enjoyed.