It's one of my big disappointments in the game... but it's because, again, we have a very basic (and stupid) whim system.. It's another huge wasted opportunity, and frankly, I end up with Sims who have no friends whatsoever because they get enough social from their family.
A much better approach would be to have Sims who want to hang out with their friends, want to call a specific friend when something good or bad happens to them, want to have a party (where people actually INTERACT instead of going to the computer, you know), heck want to make a friend and have a BFF... but no, they want 1000 dog toys instead.
So stupid. Such a shame that, in 2018, there still isn't a good life simulation game out there. But hey, at least we have a thermostat... right?