WASHINGTON — Ask Ezra Klein what prompted him to leave a high-profile position at The Washington Post to start a new website, and the answer is a little wonkish, even for the founder of the newspaper’s Wonkblog, a mix of politics, economics and domestic policy that had become must reading in the Beltway.

It was, in essence, about content management systems, Mr. Klein said.

“We were badly held back not just by the technology, but by the culture of journalism,” he said of daily newspapers, as he offered a preview of his new site, Vox.com, which was introduced Sunday night.

While The Post is an excellent publication, he said, he felt that the conventions of newspaper print journalism in general, with its commitment to incremental daily coverage, were reflected in publishing systems, which need first and foremost to meet the needs of printing a daily paper. And he wanted to create something entirely new, which is why he and two Post colleagues ended up at Vox Media, a rising digital empire that includes sites like SB Nation and The Verge. Vox, he said, had the tools he was seeking.

“At our first meeting, we knew we were going here,” he said. “They had the technology we thought we were inventing.”