People respond to someone losing their unborn baby with the same exact emotional attitude as they do responding someone writing about losing their job. They just put "for your loss" at the end of "I'm sorry".
"I'm really sorry that happened"
"I'm really sorry for your loss"
That's everywhere - not just on Bloop. I don't think it's about emotional attitude - more about social linguistic convention. People tend to say 'I'm sorry' for anything negative that's happened in someone's life. Kind of like how they say 'Congratulations' for all kinds of positive things, from having a new baby to passing a driving test. It's just people's way of saying 'That's sad' for negative things, or 'That's good' for positive things. Of course, if it's in real life, there is tone of voice and body language too, so emotional attitude (or acting of it) is easier to read.
It's not that common here in AUS, yet... But a young vet nurse said that to me after she helped put down my elderly dog. We were all beside ourselves with grief and it made me want to smash her in the face, to be honest. I didn't say anything, because I knew she didn't mean it to be a platitude.. that's how it came off, though. I hated it.