I think that “Stream 1…” example would still work pretty well if those “JOIN” buttons were appropriately styled and just linked to the group page. I strongly doubt you’d lose many people in the onboard funnel with that extra click.
Although far from a perfect equivalent, I do hate it when websites use that interactive “follow us” Twitter widget which asks me to follow them immediately instead of taking me to their Twitter stream so I can see if I’m actually interested in what they’re putting out.