Totally agreed. I started a niche site (a directory for notary publics that funnels visitors into a paid app that helps notaries manage their businesses) as a lightweight SEO experiment.

It's only been ~6 weeks but, even if I can't get many of the visitors to convert to paying customers, I've learned far more in the past few weeks than I could have learned through meetings/reading/dreaming.

First hand experience FTW.