I'm surprised there has been no mention of Adobe Muse in the comments thus far. Adobe Muse is a similar WYSIWYG website design tool. One which I've used extensively; both pre-responsive and post-responsive versions.

Adobe's Muse has been a blessing and a disaster for me as a designer. I've had to, on two separate occasions, refund deposits for projects I couldn't complete because I reached bugs in the software that would prevent my designs from working properly. Once an "update" is released, sometimes fixing these bugs, new bugs are introduced. I have walked away from the software altogether because it literally reduced my net pay due to unforeseen hours spent chasing issues outside of my control. Not a great feeling when you're stuck in subscription model.

With that said, I welcome and support software competing with Adobe's design tools.