Agreed. Reviewing on the same day the account was created isn’t really a surprising thing. If you’re not a developer, the only reason to create an account is to review an add-on or create a collection (less likely). Most users will only have an add-on or two, and don’t necessarily want to review all of them.
There are spammers, for sure, but demonstrating that they’re spammers isn’t simple, and developers also confuse spamming with negative reactions.