John always seems to forget that this is a DIY'er forum, and setting tile, adding a heated tiled floor may be the first and only time someone does it. What is simple for a pro, is often totally Greek to a first time DIY'er. Rather than helping along that path, he chooses to degrade, and discredit anyone that disagrees with him.
Trying to level the floor after placing heat wire or mats can be a little awkward. It's an acquired skill, some have long mastered, but a first time DIY'er can easily find troublesome. Ditra Heat seems like a good way to handle it. Apparently, not all people think like John Whipple, otherwise, Schluter would not have spent more than a year and a pile of money working out what it takes to make the system easy to install and reliable.
Prior to cbu, the only reliable way to build a shower was to mud the walls. THen the cbu became readily available, the rules changed some. Think about thinset...that is a relatively modern invention...prior to that, the only reliable way to set tile was quite different. It took years for people to make the switch. Then, waterproof membranes came along and evolved, with some working better than others, and the rules changed again. So, what one 'knows' may often end up wrong, as is the case with John Whipple who does not believe the testing and wants to only do things his way and force everyone to follow. Whatever you are comfortable with, just don't foist it on the rest of us, we are capable of learning.