Junior developers become CTO's of startups all the time, it's really not that remarkable, all you need to be is a co founder and since such teams are usually CEO and CTO, the roles are quite obvious.

The main mistakes that junior engineers make when they accept the role of CTO is to think it's a 100% technical job. It's not, especially when you have fewer than 30 employees.

The CTO title is pretty meaningless unless the company either has > 30 employees or has at least one successful product.

Becoming a CTO isn't that hard. There are tons of startups out there that are dying for a technical cofounder. The vast majority of them are not going to launch a revenue-generating product, let alone survive. Maybe it's a decent option if you can afford to go without money to build experience. But given the long odds, the opportunity cost is no joke. And if you've chosen your team poorly, you're in for a bumpy, frustrating ride.

Becoming a CTO of a company that can afford to actually pay you a salary, is tougher. Now, you probably need a solid track record of achievement, because they can afford to be choosy. Maybe even choosy enough to just make you "SVP of Engineering" instead of CTO. They'll want you to have shipped products you played a leading role in building from the ground up, to be able to build and lead an engineering organization, and to have very strong business sense. But now you've got the financial security of a salary and the tremendous upside of a founder's equity stake.

Becoming a CTO of a company that's actually growing is even harder, because you actually have to be competent enough to have led that company from some venture crazy enough to take a chance on you to real traction (at least on the investment front) and success. This really is the hard part, and I think that's what makes the author's perspective really valuable.

The OP worked for Google for some period starting in 2006 and then went to a funded startup called RedBeacon at some point after they were founded in 2009. RedBeacon had an exit through an acquisition by Home Depot in early 2012.

So to recap, the OP was an ex-Googler, who had been an early stage engineer at a funded startup which got a pretty massive exit. Who wouldn't want this person as a CTO? :)

Co-founding a company doesn't hurt in becoming CTO.

(Disclosure - I know Ian, the author of the article, and a few Artillery employees)

The majority of the time, becoming doesn't CTO involve being the best technically/business wise. Just being there at the right time, I.E Early employee or co-founder.