Even with group functionality, Steem will be very open platform where users are constantly exposed to different topics. I don't think trending-page should disappear, so seeing what other users are doing will only a one click away.
And because Steem is a public blockchain, groups won't be secret societies. They will be open for everybody to read and follow.
If you don't like groups, how would you solve the "too much noise" problem? Users are already seeing too many posts so that many good ones will be forgotten immediately, or even not seen at all. Good writers don't get the attention they deserve. It discourages new users because they can't get any followers. Without groups, it will be very hard to get any upvotes or comments in the future because there is just too much content.
Subscribing is your first group, hashtags your second, muting your third, how many walls do you need to isolate yourself sufficiently?