For another perspective, directed to a similar blog by DHH but about the same arguments, read: https://www.destroyallsoftware.com/blog/2014/tdd-straw-men-and-rhetoric
I think Gary has the better argument. DHH claims that that "you don't need to diet, you look great just the way you are. Just eat better, and you will be beautiful." It's a happy dream that just isn't true. You can't hit the delete key and suddenly have a buff body -- you need to diet, exercise and adopt healthier habits if you don't want to be fat and unhealthy.
Simply rewriting systems as the solution to flabby, fat and bad code
-even if it is french poetry-
is a fantasy, economically irresponsible and unprofessional. When the proposed practice is being justified with straw men, four-letter words, Fox News-style claims that "some people say," and "I've looked a few times and every single time" arguments, it is suspect.
I think Gary made a sound, balanced argument. It feels good to be told you aren't fat and don't need to diet. But it isn't good, at least for me. I am flabby, out-of-shape and the disciplines of Software Engineering made my code cleaner and better. Maybe you are all buff coders, and good for you. But is that also true of the rest of your team, the people you will hire to replace them? Disciplines are good idea. Just apply them correctly, and don't argue against them by making arguments that NOBODY who gets it really makes.