Yeah, it doesn't do a ton for you, but it's not really meant to be a primary strengthening routine in my eyes. I like it as a light mobility and strengthening routine on recovery days. It's also pretty good if you've got no equipment available and you are confined to a pretty small space as well. It can be done pretty much everywhere. I typically do it after a run, but it would be good as a pre-run routine too. It's a routine that you really get out of it what you put into it. You can feel it a little if you really focus on doing every rep slowly and getting through your full range of motion. You could also easily add a resistance band to some of the exercises too.
As far as distance running goes, as we all know, nothing substitutes for consistent mileage, lactate threshold work, and other running specific workouts. All the ancillary work should allow you to do all the running-specific work more consistently. So that's what I think the Myrtl routine is - something that doesn't tear you down much at all, but can be enough to prevent some kind of ache or injury, although not everything. As I said, this shouldn't be a primary strengthening routine. There's my two cents for what it's worth.