With responsive design - that adapts to your viewer, their bandwidth, their device (and orientation), their add-ons (eg uBlock/ABP) - WYSIWYG rather starts to lose meaning. I'd warrant it's easier to design in the abstract than moving elements and watching 5, 20, 100, ... different views to see what your page visitor might see.

Now add in progressive enhancement.

We're not dealing with the largely fixed desktop viewport anymore.

That I suspect is why WYSIWYG hasn't taken off, Dreamweaver did quite well, but then the web ran away to multi-platform as the default.