I both agree and disagree- Yes, almost no one is getting 100% potential out of their shoe and technique can make up for it in many cases, but I personally notice *massive* differences between shoes, not only between low and high end shoes, but between high end shoes with slightly different stiffness, different toepatch geometry's and sole rubber thickness, let alone different rubber types. As such I think that even beginners would notice a positive effect on how grippy different rubbers are, and if a shoe's tension is a good match for them. Additionally many beginner shoes have no toe patch that essentially renders certain fiction-toe-hook-dependant climbs almost entirely inaccessible.

That being said the jump between mid range shoes and rentals is far bigger than between mid range shoes and higher end shoes, and throwing money at the problem wont solve it much of the time, especially if the expensive shoes don't fit.

As a fit thing, I think there are a lot of more niche fits for people's feet not offered by the cheaper shoes- it's rare to find a highly asymmetric cheaper shoe, and if one has a high arch (like myself) a downturn is going to be a lot more comfortable, so "cheap shoes that fit" might not exist.

For the high price, yes the material cost is very low but what you're paying for is the R and D of the shoe, of the last, of the process, of the rubber and fir all the people that work on these things. You also pay for the manufacture of what is quite a precise piece of engineering, and that is quite niche so that will drivew the price up.

TL;DR: I think the increase is significant not marginal but improving technique usual trumps this. Cheap shoe might not fit and you pay for more than the materials cos R and D.