Maybe I'll leave the readers of both our contributions to decide who's the academic between us.

It would seem that you actually do not understand what cryptography is in the modern sense.

A fundamental nature of information is that it wants to be freely copied everywhere to everyone. That any bit is equal and indistinguishable from any other bit of the same value and that any bit is eventually known to all who care.  Cryptography is all that technology by which we hope to confine and constrain the nature of information, to put up fences and direct it to our exclusive purposes, against all attacks and in defiance of the seemingly (and perhaps actually) impossible.  Digital signatures are cryptography by any modern definition and utilize the same tools and techniques (for example, a DSA signature is a linear equation encrypted with an additively homorphic encryption), and suffer from most of the same challenges as the message encryption systems to which you seem to be incorrectly defining cryptography as equivalent.  Moreover, the use of digital signatures isn't the only (or even most relevant) aspect of cryptography in cryptocurrencies-- e.g. the prevention of double spending of otherwise perfectly copyable and indistinguishable information in a decentralized system is a cryptographic problem which we address using cryptographic tools, and-- like all other practical cryptography-- achieve far less than perfect confidence in our solution. As are more modest ends like interacting with strangers but not being subject to resource exhaustion from them.

Far more so than other sub-fields of engineering, cryptographic systems are doing something which is fundamentally at odds with nature and share an incredible fragility and subtly as a result (and perhaps all are failures, we have no proof otherwise).

A failure to understand and respect these considerations has resulted in a lot of harmful garbage and dysfunctional software.