idk, many possibilities
Correspondence Tournament Question
Not that 5 games is going to give you an accurate rating, but it is better than nothing.
Who cares if someone's rating is inaccurate? Especially on an open tournament.
The reason is to demonstrate you will follow through and finish a turn-based game that can take months to complete. Nobody wants to start a tournament with players who will decide they don't like this form of chess and just quit. Completing a few games shows you can finish them and have some idea what it's about.
Is the fact that the rating is not accurate a component as well?
What is the reason for having to play at least 5 online chess rated games in order to participate in a correspondence tournament?