To get your degree from a school indicates that you demonstrated some abilities in a selective and competitive environment. The quality of the school tends to imply the level of quality vetting -- to get into MIT is more competitve than ITT. The name on the commercial experience reflects a similar vetting process -- a development job at Apple is more difficult to obtain and maintain than one at a local utility company. Arguably, a job at a notable startup is probably another strong indicator (on the idea that a startup can't waste time on inferior talent); but I wouldn't consider job upgrades at an unknown startup to indicate much (ie, everyone here could be a CTO or lead developer for their own startup... does two years of being a lead developer for a team of one to three, selected by company seniority, tell you anything about technical leadership ability?).

It is all just borrowing collective intelligence -- using the wisdom of previous crowds to give off quality indicators.