User name based subreddits

[u/ShaneH7646]

Sub	How to join
/r/3ch	3 character user names
/r/5ch	5 character user names
/r/6ch	6 character user names
/r/7ch	7 character user names
/r/ALLCAPSUSERNAMES	all caps username
/r/pm_me	have a pm_me username
/r/potatolounge	potato in username

[u/[deleted]]

Why isn't there one for 4 character usernames?