As a proactive use (and with misgivings of causing offense to Mark) I'd recommend an effort to quantify and total 'Likes'.
My usage as a non-email group owner and member of many, is to create (other than by bookmarking/ favourites) - my own or others visible to use as a tracker for valuable, cogent or specially usefull information (i.e. my main area of interest is historical groups and photographs etc.).
As there's no other way to highlight useful/ efficient/ accurate information contained in or attached to messages, other than copying each and every piece of documentation/ text out to a separate database. Maybe a sidebar link or under the 'Topics' pull-down menu (listing personal and all sub-menus perhaps?).
I do not require- tracking others; counting group or egotistical targets to be shown.
Thanks for reading,