I disagree. While it's true that early cryptocurrencies were based on well established cryptography, a lot of the modern (post 2017-ish) cryptocurrency tech involves cutting-edge cryptography. Especially with respect to post-quantum setups, zero-knowlege proofs, and new devices like adaptor signatures.

One reason for this is that cryptocurrencies are highly bandwidth-limited. Cryptography developed for other applications (such as voting systems, etc.) needs to be specialized to meet the size and computational restraints inherent to cryptocurrency design. Efficiency is everything.