IMO what you're saying is a bit confusing. Of course you want to regulate according to some standard. Otherwise folks just dog it. We see that all the time here, where folks think they're going hard and doing intervals and it's obvious they never get above mid zone 3. If you're really going to TRAIN, you have to test and train w/r to that test. Otherwise you're JRA. Intervals are supposed be hard. If the rider doesn't want to experience the pain and trauma, no need, just ride.
So not limiting to a response to your argument, only to your title, there is a genuine discussion out there about whether to follow FTP or HR when doing intervals. IOW, whether to allow HR zones to change through drift while riding some percentage of FTP. Which is physiologically more productive over a many week training schedule? Now that's an interesting argument. If that's what you're arguing, you could have been clearer. I've read a study which suggested that in the case of HIIT, following HR gave better results than following power. My own training suggests that there may be a larger case for that, depending on the training content and goal.
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Results matter