Linn has chosen their approach and they are entitled to present it in the best light and anyone else with some experience on the topic is entitled to criticize their choice and their presentation.
I agree with you. Everybody, with proper experience, is allowed to criticize their choices.
I've used both, and I find the microphone method cumbersome. Maybe I'm a putz, but I could never get two sets of measurements to look the same. As such, I prefer Linn's. Distances are exact, and Linn does a lot of work modelling the speaker in their labs (not only Linn's own, but a lot of other brands). You're still not getting the point of Linn's product: reduce complexity. Again, this feature was added to existing product. Linn could've mailed out a microphone, with a 100 page manual, with a big "GOOD LUCK" in the end... But they opted to make it simpler, at least in my eyes. You can probably perform mic-based room measurements in your sleep, but a lot of people can't, and most importantly, don't want to.
As I said, it'd be fun to test both methods, as well as their implementation side by side (Linn's and DEQX's, for instance, or DIRAC's).