Any technology that we built is used for both good and evil. For example, assembly was used to get people on the moon, but also to navigate missiles to kill millions of people. Perl was used to sequence the genome, but also it was the main language that script kiddies used in the 2000s to deface millions of websites. Almost any library written is dual use, from openssl to left-pad. The web itself is used to enable world wide education and giving everybody access to all the knowledge in the world, and is also responsible for the fall of democracy. Torrents and peer to peer tech is also with interesting ratio.
Of course the good:evil ratio is different for any technology, but this also changes with time.
It feels weird to me to draw the line at crypto. A good example for the debate would be 'why dont you remove the torrrent projects as well, given that torrents are almost exclusively used for "illegal" activities'
PS: I really hate cryptocurrencies :) but just got interested in: why do you draw the line there?