Discussion and idea swapping and socializing is and should be so much more than just liking something. The like function is going to just create more noise. It’s no where near as useful as a bookmark or hyperlinks.
Alas like so many innovations on the social web it’s just more naive data collection. Digging, checking in, liking, stumbling, retweeting…. Ugh.
Tagging, linking, and commenting at least encourage some creative effort.