Its a form of Dunning Kruger.
First of all, how do you know you are good? If you are guessing (or imagining) you aren't good. This implies you need something to measure. Secondly, how do you know what to measure? If you don't know what to measure you have no idea whether you are good. You could be good, but you have no ability to determine this. Third, if you do know what to measure you need to know how to measure it. If you don't know how to conduct those measures this is where reality begins to set in, because you know enough to determine your competency but not enough to qualify it. Finally, if you know how to conduct such measures you have to determine their validity and that just takes experience, such a various forms of competing measures.
If a person can make these measured determinations with a few as 2 years experience then they are likely excellent. Excellence isn't at question though. Its the ability to appropriately determine excellence that matters.
Dunning Kruger is typically the opposite of gatekeeping. Its where under qualified people believe they are better performers than other people determine them to be. That distortion of reality is often on full display in embarrassing fashion to those making the determination and third party observers. If gatekeeping were in effect under qualified people would not be provide these opportunities to embarrass themselves.
