2015's Argon2 publication suggests that cryptocurrency hashing like password hashing on backend servers should not be subject to side-channel attack:
Argon2d is optimized for settings where the adversary does not get regular access to system memory or CPU, i.e. he can not run side-channel attacks based on the timing information, nor can he recover the password much faster using garbage collection [17]. These settings are more typical for backend servers and cryptocurrency minings.
Why ?