"The latter serves more or less the same function as a post that just says "+1" or some such -- it's a form of noise."
No, no it doesn't, and no it isn't.
It is a neat and efficient way by which members can identify threads that are highly informative or that have other demonstrative merits above and beyond the majority of the threads posted here.
Just because you "like" something and wish to express it doesn't immediately drop you to the level of vacuous spreader of meritless drivel.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.