A horse changes shape when it moves. This is true of ALL horses, of any age. A saddle that fits perfectly "static" will, by definition, not be "perfect" in motion. So we don't seek "perfect" fit, we seek an "accomodating" fit.
As to "angles," maybe so and maybe not. Different types will have different shapes and those different shapes call into question any assumption of what angles "ought to be." Further, the fit of a saddle must take into account the use of the horse. If you're going to foxhunt (or work cows in rough country) then you're going to need to think about some things that somebody who's doing nothing but Dressage (or Western Pleasure) need not worry about.
A saddle fitting is not a bad thing, but as with all things depends upon the skill of the fitter and who the fitter is working for
. If you see a Stubben logo on the fitters truck then that gives you a hint where their recommendation will take you. Again, this is not necessarily bad; only that it will, necessarily, strongly affect the fitters recommendation (which may be quite correct in all of its particulars).
I've no opinion on Crest Ridge saddles as I've never seen one. I've looked at the website and it's designed to sell me a saddle. So are the URLs for Stubben, Passier, Black Rhino, etc.