A proof-of-work (PoW) system (or protocol, or function) is an economic measure to deter denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester, usually meaning processing time by a computer. The concept was invented by Cynthia Dwork and Moni Naor as presented in a 1993 journal article. The term "Proof of Work" or POW was first coined and formalized in a 1999 paper by Markus Jakobsson and Ari Juels. An early example of the proof-of-work system used to give value to a currency is the shell money of the Solomon Islands.

Based on this passage, what is the point of proof of work? Let's give stream of consciousness first:
To answer this question, we should know that: A proof-of-work (PoW) system (or protocol, or function) is an economic measure to deter denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester, usually meaning processing time by a computer.
So, the final answer is an economic measure to deter denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester , usually meaning processing time by a computer.