I'm sorry for your loss, Reluctant. I'm in a similar position - my dad died just over a month ago.
I, too, was quite shocked by how little acknowledgement I had. I think I got 6 cards, and my best friend sent me some flowers. That was it.
I was more accepting of people who didn't come to the funeral, because I know it's hard to drop everything (and some people were on holiday). There was a decent turn out, and it was of people who were important to my dad, and to our family.
However, I did also announce it on Facebook. I see no reason why not? Once all our closest, nearest and dearest were informed personally, Facebook was a great way to let all my other friends and contacts know of his death/my bereavement.
And I got lots of messages of sympathy that way.
So I think it's just about times changing.
I'm very sorry for your loss 