Quite simply, it is what you mean precisely by the term "truly composers"; perhaps my inability to understand the motivation behind your question is because I have never knowingly composed other than "truly"...
Best,
Alistair
I knew this was coming, and it's a valid point.
If you want to follow a simple definition, then anyone who writes music is a composer; however, this is the equivalent of saying that anyone who writes a poem is a poet. I am quite sure Shakespeare wouldn't like to be equated with Joe Blow. On a lesser level (I doubt there are any Beethovens here - myself included - for sheer statistical reasons, if nothing else), I think it is still important to distinguish those who have actually worked hard at acquiring a solid craft from those who compose music that a 4 year old could compose by accident.
There seems to be a very popular misconception that composers are simply born with all of their gifts in hand. As you know, even Mozart (arguably the greatest child prodigy of music in history) studied religiously, first with his father, and then with other contemporary masters (e.g. C.P.E. Bach, Salieri) and masters from the past (e.g. J.S. Bach). The point is, many composers (usually the ones of lesser ability) seem to think that they are channeling the voice of God when they couldn't even begin to go into detail about what is wonderful about a certain piece by, for example, J.S. Bach.
I think this is one of the very unfortunate outgrowths of post-modern thought: everything is equal and difference only arises in terms of subjective opinion. I think this a great assault and disrespect to great art.