You could say that, but I’d argue that comparability of workouts is important for gauging progress. If, for example, I try to complete a Gorby workout (5x5 VO2) with the intervals at 340W, I know that I’ll be working right at the limit of my capability; to fail one week in the fourth interval, and go on to then succeed the next week, would be a sign of improvement and a significant psychological fillip to me.
That’s not to mention that I’m sometimes/often completely out of my tree when I finish a hard interval. Watching little numbers on my handlebars, trying to nudge them towards a particular value, while staying safe on the road… not for me, thanks. I’ll make use of the erg mode on my turbo for that.