Topband: QRP Question

[W0UCE]

Maybe and experienced QRP OP can answer a question for me and please note
the question is not intended to anger anyone or start a flame. I would just
like to learn something - "Why?" 

So here is the question:  Why do some using QRP continually send /QRP after
a CQ, their call or a contest exchange?  In a contest I don't care if the
station I work is QRP, LP or QRO - a QSO is a QSO.  

The same when calling CQ or during a rag chewing - Why send /QRP? To me it
makes no more sense than someone sending /100w, /LP, /1500w or /QRO after
their call.

73,
Jack