There’s a lot of magic with Vercel, but I think the true “wedge” was clear to many people: DX. The trick was really the execution, which they nailed. They realized early that there was a whole class of developers out there, many of them quite talented, who couldn’t stand SSH’ing into Linux boxes, configuring htaccess files, installing SSL certificates, etc. Many of these developers also worked at big companies, and held sway.
They distilled the entire deployment process into a few clicks and boom, you have a real, functioning, fast website. Then they added templates, good marketing, and doubled down on React. The rest is history. It’s a well executed vision and I give them a lot of props for that.