An interesting side effect of a young world could actually be the possibility of finding more metals in their "native" forms, such as gold and silver on earth. Native iron can be found on Earth but is mostly (or entirely) from asteroids. A young planet where iron and other metals have not succumbed to oxidation and other effects might actually be considerably richer in many metals at a primitive stage before smelting of ores was commonplace. Not saying it is a certain thing, but it is possible. No scientist here! And really young isn't necessary, per se, just only recently habitable in geologic terms, or from a planet where there was never a truly vibrant period of life to die off and become fossil fuels. Would a smart dinosaur been able to drill for crude?

The most plausible to my ear for holding back progress is a lack of fossil fuels, which is a piece of what holds back technology in my world. In addition all attempts to harness energy too tightly (even steam power) is extremely dangerous due to the Elemental (magical) nature of the world. Gun powder is much like packing highly volatile nitroglycerine through an obstacle course, LOL.