Neurons exist with a deterministic locking period to ensure that voters are tied to the outcome of their vote for a specified period of time. The purpose is to align incentives. Voters who are willing to lock for significantly longer get more VP per ICP. The primary reason is to ensure that anyone who votes is voting with a medium to long-term perspective that should be intentionally in the best interests of the network as a whole - the longer the term, the higher their VP.
Do you agree that this is the main purpose of neurons on the IC?