"Real musicians play in a real band they don't use cheesy home keyboards." LOL

I'm just kidding,

I think you should use the tool that suits your needs best, If you want to perform solo (and you don't want to lower yourself to midi files and true karaoke), there's no other option than the Arranger keyboard, you can't let a full virtual band play and let it do whatever the player demands on a synth workstation, they just don't have these capabilities, Arranger keyboards and workstations are two different cups of tea, like apples and oranges, However I think if you are really into composing, I think a synth workstation is a much better option, and maybe even better, a combination of an arranger and a synth.
We all have our own ways of creating music, whether its using an arranger, synth workstation, piano, software etc.
There's no need to disrespect each other for our ways of doing things, or to call people "unprofessional" because they choose to use different tools than you do.

Greetz ,
Marcel