The component of your writing I'm referring to is in How to Make Wealth: "If you wanted to get rich, how would you do it? I think your best bet would be to start or join a startup." Your other writings had really resonated with me, and you had described Viaweb's hackers as really risk-averse, so I assumed that I was among the "you" comprising your target demographic. But, having been exposed to other methods of getting rich, I no longer believe my best bet is to start a startup. I would also guess that it is not the best bet of the majority of your readers. It is possible that I am underestimating the prowess of your readerbase, or that you are not writing to the majority of your readers.
I'm happy that you provided an alternative viewpoint at Startup School - I'd love to hear you address the possibility of getting rich via a 37 Signals model on your blog. I know you've mentioned why you don't invest in software companies in order to obtain dividends (despite the fact that people do invest in things like restaurants and banks in order to obtain dividends, and, as an investor, I think I'd rather own shares in a profitable software company than in a profitable restaurant). Maybe you could tie it all together into a blog post at some point. The topic appears here frequently.
A startup is a company that creates wealth rapidly by creating technology a lot of people need. While I don't know the details of 37signals' finances, it seems likely that they'd count as one by my definition.
I think the thing that makes people think 37signals is not a startup is that they currently seem to have no interest in selling the company, but instead pay themselves a lot of the revenues as dividends. That's a matter of personal preference, but as I explained here,
they amount to the same thing.