Posts published on Groups/Events/Persons/Organizations Timeline aren't shown on main site TImeline, because they are in the context of these pages, they maybe irrelevant when posting outside of these pages.

We've made Groups/Events/Persons/Organizations Timeline very similar in principles like other social networks (like Facebook). But Homepage Timeline isn't available anywhere and we've used own approach, and it maybe different vision on how it should functions and we've made what we think is most usable and logical and use it for own sites too.