For personal, 1:1 contact, a little goes a long way. On a couple levels.
First off, it really takes very little 1:1 contact to maintain a deep relationship - no more than 10 minutes a month on the phone for some of my most meaningful and long-lasting friendships, sometimes less.
It's true that, without the Facebook feed, I don't get a play-by-play of every single even that happens in their life via the Facebook news feed. I see that as a positive thing - it leaves us with something to talk about when we do make time for each other.
Second, I definitely am in contact with fewer people than when I was on Facebook. The relationships that I have maintained since then have been more fulfilling, though, so, at least as far as I'm concerned, it's still a net positive. (Think of it as giving your social life the Marie Kondo treatment.) I'd like to think that's a two way street - if I'm getting more out of the interaction, then that means I'm probably giving more back, too.
So the end result is that my friends are not, overall, spending that much time interacting with me without Facebook. I can't speak for them, but, I at least view it as an enjoyable way that we can spend some time together, if not physically in the same space. I'd like to think they do the same. It'd be really weird if they thought of me as a friend but didn't actually enjoy having conversations with me.