I think most people will agree that bar position relative to the saddle will change drastically depending on application. Commuting vs crit racing vs group riding vs gravel epics all will demand various degrees of long/short, wide/narrow and high/low.

I think what is more contentious is whether saddle position and crank length ought to vary depending on application. Of course, you have some external considerations like fixed gear crit bikes needing shorter cranks for corner clearance or TT bikes needing shorter cranks to allow for breathing and pedaling in a flat back position. But barring those, I think there are many who think there exists a perfect, optimal saddle position that works for all applications.

I don’t believe that to be true. I think, for longer, slower rides, you’d want to be further back and low (think beach cruiser) and for harder, hillier or shorter rides, you’d want to be slightly further forward and up - maybe even slightly tilted. In the end, the range of power you can deliver doesn’t vary all that much. So you’re not going to need drastic changes to saddle position. But I personally believe there are optimizations and compromises to be made.