I don't agree. I am only an amateur songwriter but I don't think you can generalise, Guest. You are entitled to your opinon, of course, if you were not just being provocative.. lol! :-)
I think some songs are ones created... of 'the moment' others are created painstakingly with care and deep thought over time. Sometimes you start a song, get stuck, leave it ages, then suddenly something sparks off the rest of it.
I think songwriters work in many different ways and also, the same person, may write in a variety of styles, depending on their mood, or choice of subject matter.
I also write differently, depending on whether I write at the piano, with my accordion or starting with the lyrics on their own, out somewhere.
Surely it is good to write in different ways?