I was thinking of things like deploying auto-scaling SOLR clusters for hundreds of dollars, vs tens of thousands for dedicated search infrastructure years ago - maybe a bit more than 5 years, but that's the gist.

Twilio. Maybe Twilio is within the 5 year window too.

Mobile apps in general - the hardware infrastructure in peoples' pockets lets us do stuff with software that was not on most peoples' radars 5 years ago.