When my son was born, I sent an email to a select list of people announcing his birth, weight, and that wife and son were fine. Standard fare for the occasion. He graced the world around 4am Eastern time, and I felt calling anyone was beyond my energy level and of little value since the closest family member was 1,200 miles away.
When I spoke to my mother two days later, specifically calling her to ask why she hadn't responded to the email, she was upset with me for not calling her immediately. Apparently an email to a bunch of other people was beneath the status of our relationship. My mother (who I rarely speak to more than twice a decade) believed she deserved to receive better communication and access to me than the friend who had keys to my house and was watching my dog while we were at the hospital.
These relationship distinctions are interesting, but I feel like they are becoming a thing of the past. My younger friends, even close ones, are fine with "personal" announcements happening on Facebook, in public. Basically, everyone who is a Facebook friend finds out at the same time. If you are interested, great: engage, like, or share the post. If you aren't interested, great: ignore, unfriend, or engage as a troll. But since nearly everyone is treated as equals on the network, the author is absolved from having to make decisions on which friends were called first, and when; even better than what I did, since I had to choose the email address for the to: line.
When it is truly a private conversation, my inner circle of friends tend to share over Signal or Facebook Messenger, more peer to peer mechanisms for communicating. But those are for incredibly private conversations. The kind where you are asking a good friend for something that should never be shared, and there will never be more than 2 people total in the conversation. But the list of people that fall into this category is down to 2, all of which I have regular physical, face to face interactions with.
I think that if you are comfortable sharing something online, then you aren't sharing too much online. If you are uncomfortable sharing it online, or with what other's are sharing online, you might need to reflect on why you feel that way. It likely has to do with a belief that you have a better interpersonal relationship with someone, a better bond with that person, than you really do.