There was a time when they were popular. Then, such tools were declared "uncool" (not without good reasons - the markup wasn't particularly good) by semantic markup movement, around the time of tables-vs-divs wars.

Semantics had withered away since then. No one cared, and it eventually got replaced with a bunch of <div>s on the DOM side and JS-virtual-DOM-all-the-way on how it's generated and managed. Editors haven't caught up, but I'm sure they will.