Whats the point of all the hype surrounding high-end rear derailleurs, are they really worth the investment for gravel grinding, or is it just a marketing ploy to get us to part with our cash, and if so, whats the best budget-friendly option that can still handle the demands of gravel riding, and are there any real-world differences between Shimano, SRAM, and Campagnolo when it comes to performance and durability in this type of riding, or is it all just marketing mumbo-jumbo, and what about the newer players in the market, are they worth considering, or should we stick with the established brands.