Do you consider FDC’s relevant to a classical stamp collector? No! Unless it is a letter carrying Penny Black sent on the date of issue or a similar item from before the concept of FDC's were invented. Could even very well be of a later date if genuinely a letter reflecting the proper postal rate.But why are FDC's not terribly popular among advanced traditional collectors? Because their postal purpose is questionable. They are wannabe letters, but never become letters. A letter is basically a message to somebody who is absent. If the receiver replies you even have a correspondence. FDC's do not carry messages, they just mark an event. The stamp on an FDC furthermore often does not reflect a rate for services rendered.
These facts do not mean that FDC's cannot form part of a stamp collection. I am sure thematic collectors wellcome them. I myself include FDC's in my open class collection. They represent my theme and add to the variety of objects. Whether they fall in the category of stamp related material (50%) or non-stamp related material (50%) I do not know. The judges will surely tell me if the balance in my collection is out of order.
FDC's should be accepted for what they are. A collector's item marking an event. Problem is that suffisticated dealers sometimes make unexperienced traditional collectors believe that FDC's belong in a traditional collection and even may gain in value like traditional stamps and covers sometimes do. FDC's, however, very rarely do gain in value to the great disappointment of many a young collector!
