I won’t mention here as I don’t want this post to come across as promoting cryptocurrency, but this script was originally written to protect a faucet for a cryptocurrency that does exactly this (and has been since 2012). This cryptocurrency records user contribution to various computational projects (BOINC, Folding at home, etc) and can also be used for torrent seeding or other forms of contribution. So it could be used in this manner to verify a user has contributed X amount of computation over Y time periods.
The faucet handed out coins but the problem is that users want all the free coins right? But we only want to give a few free coins to each user. So we make them do the “work” and make sure the cost of work is > value of coins, so they have no motivation to hit the faucet multiple times. This is the original purpose of the script.