I cannot find the study to link but this one is pretty similar https://www.goodtherapy.org/blog/psychology-facts/how-many-f... Basically 8 is the number of really closest friends a person has. Also we have Dunbar's number https://en.wikipedia.org/wiki/Dunbar%27s_number
So 8 and 15 sounded like the choices on spot, but I added some padding for new promising friends and "hobby friends" (the folks that are not super closer but where you have lots of activity time).
So the limit is psychological and the padding added was to not block users with analysis paralysis seeing a slot like precious.
UI considerations:
I wanted a snappy way to select your friends, they should enter in a fraction of the screen, not a long scrollable list, not a search input.
Increasing
I hope this is not needed, the closeness is by design. But I understand we are bad at deleting friends. I'll see how it goes.
It slows down the service’s growth. Most social networks exist to make the creator money, not to improve your life.
Social networks with a small maximum number of connections aren’t a novel idea[1]. When we struggle to recall any, it tells us how successful they’ve been.
That all said, I wish Ferris the best of luck. It would be a losing proposition to try to get my circle on it, but the idea seems to come from a good place and I hope it finds its audience.