Of course no one will ever agree or come to any kind of consensus, have we ever, about anything?
But a single line of poetry has always struck me as more of a quote or something. A proverb or adage but not a poem. Though, according to definition, it is technically a poem.
MONOSTICH (MAHN -uh-stik)
A
poem or epigram of a single metrical line.
(Compare Distich, Hemistich) from -
http://www.poeticbyway.com/gl-m.html - emphasis mine
mon·o·stich [mon-uh-stik] –noun 1. a poem or epigram consisting of a single metrical line.
2. a single line of poetry.
[Origin: 1570–80; < LL monostichum < Gk monóstichon, n. use of neut. of monóstichos consisting of one line of verse. See mono-, stich] from -
http://dictionary.reference.com/search?r=2&q=Monostich
In the end it's all just opinion. As has been said many times, just take what you want, what helps you from a critique thread and ignore the rest. Who really cares what people on a forum say?
It's my opinion that the current state of the critique section (no rules, no guidlines, no limits, etc) has led it to become of little use anymore. When you have a front page that continualy has 2, 3, 4 poems each, by a couple of different users, and people generally not going beyond page one to look at poems for critique, and very few people critiquing in the first place, not a lot of quality feedback is going to take place for many people. All you can do is accept what you get, take from it what you want, and go on. Or, find another game.