Oh wow, for some reason I misread and thought this was a relatively new game. Yes, by all means turn on the Allow Celeb in SP (it's not a MasterController command, it's strictly SP) as that would be throttling things so that they never even get started. "Friendship" is the general NRaas category that the celeb system falls under, that doesn't mean its focus is restricted to social interactions with what we call "friends."
It may be easier and you may want to go ahead and allow celebs to overrun the town actually and then work to restrict them. I usually work with all of the ways to get celeb points kept on but set very strict celeb level ratios so that after each level is filled up, no one can enter it from below until someone else moves further up,drops down, leaves town, or dies.
NRaas > SP > General Options > Options:Friendship > Options:Celebrity > Celebrity Ratio Levels (1 through 5).
The defaults are 100/50/25/12/6. Depends on the world I am playing and what I want to see happen, but I'm much happier with values more like 20/10/5/2/2. But also think about your world resident population. If you have 150 resident sims for example, then a cap of 2% is 3 sims (for Levels 4 and 5 each). Is that enough? And a cap of 20% at Level 1 would be 30 sims. Is that enough or too many?
Math can be fun, can't it? :p