I think this is a broad generalization. I work on two different projects that both invest heavily in Google AdWords and both have revenue small enough to be con

I think this is a broad generalization. I work on two different projects that both invest heavily in Google AdWords and both have revenue small enough to be considered a "start-up." If a start-up is focused on a particular vertical, or is a solution people are actively searching for, or has a revenue model built in from day 1, then advertising makes a lot of sense.