Are'nt definitions mixed up here ?
a. musician
b. 'real' musician
c. composer
d. arranger
e. bandmember

Personally I see no difference in needed skills for a (real?) musician that is a band member and a musician using an arranger keyboard : The arranger in fact IS the band !

Only very few musician are good composers.
Not every composer is a good arranger.
Many highly trained/educated musicians cannot play one single note without sheetmusic..... are they 'real' musicians or 'score-player robots'?
Other musicians cannot read one single note but play fantastic music. (Ever heard the Rosenberg Trio ?)

Please do not put lables, depending on what gear/methods we use. We should respect all musicians...... ;-)