Many Devv Community tasks are open to anyone who wants to join the community, so what prevents someone from creating multiple accounts and completing tasks multiple times?
Nothing specifically prevents that or a number of other types of cheating, but cheating in that way won't be effective in the end.
The reason is that Devv Points can be converted to Devv (per the Devv Community Terms and Conditions) using only one email address associated with only one person who has performed Know-Your-Customer identification. When someone does KYC verification, they need to prove their identity (for example, with a passport). Then we will associate one email address with that person, and verify all points for that email address, making sure all of the tasks that were done were done correctly, before any Devv Points can be converted to Devv cryptocurrency. It is a thorough process, so although there are likely to be holes where people can earn Devv Points by cheating, when it matters, those cheats won't get someone ahead, and any points received through cheating won't have value.