I don't know how you define "startup", but if you mean a Bay Area-based venture-backed software company with less than, say, a couple of hundred employees that'

I don't know how you define "startup", but if you mean a Bay Area-based venture-backed software company with less than, say, a couple of hundred employees that's been around less may, say, five years, then they most certainly do. I have worked for two such companies that made a fair bit of money. One of them even had their own direct GSA schedule, if you think that going via a reseller doesn't count. (For the purposes of this thought experiment, of course it should.)