There are plenty of use cases where someone would need to edit the Opportunity's Created Date.
Here's one:
One of our Sales people is about to start using HighLevel and he needs to replicate his existing pipeline within, which will essentially be creating a bunch of new Opportunities. Without the ability to edit the “Created Date” for Opps to reflect when these actually came into his pipeline, our data/reporting thinks these were all created on the same day. We know when these Opportunities arose... we just have no way to import or change that date field.