I'm one of the co-founders and designers at Webflow. I have never coded an entire site by hand, but I built this entire responsive site in Webflow. This WYSIWYG doesn't disregard how the web works - users actually have to know some CSS to build a responsive layout. This restriction limits a lot of Average Joe's (so no Geocities here). I actually learned all the intricacies of CSS by building sites in Webflow. Same goes for the designers out there using tool and building actual sites for the first time.

It boils down to investment and return. If designers can build responsive sites faster and easier with great code output (see source code) using a WYSIWYG, then it makes more sense to invest in that versus learning how to write the same code. Front end devs use frameworks like Bootstrap and Foundation to cut development time. Webflow serves the same purpose, but all the framework components are made visual.

This visual abstraction makes it more accessible for more people just like these frameworks made web dev easier. There is always the possibility of people using Webflow and creating poorly-coded websites, but anyone trying to code can do the same.