OD&D from 1974 was not limited to 3 levels. It has charts for 16th level Magic-Users.You could always play the game as it was originally intended and that was with three levels. The only reason they added more levels was because of AD&D.
Most young people today don't realize that D&D in it's current form is still the Advanced version which is why there is bell curve to comprehend and retain the rules and mechanics to some extent.
Anyway it's probably too late to do these kinds of restrictions, since video games enable you to play godlike characters and real gods.
You might be thinking of the 1981 Moldvay Basic Set which covers 3 levels but even that has some (incomplete) rules and references for some higher level stuff and notes there is an Expert Set covering levels 4-14.