As one that uses tracks primarily, I’m in your corner on this one Henni, but I usually have to moderate my own opinions on this by remembering this is still an ARRANGER forum (and by extension, an arranger PLAYER’S site) so I have to keep this in mind.

Use BIAB to create your track, it then becomes immaterial what device it’s played on, arranger, workstation, laptop tracks player, even a smartphone!

There’s one other aspect I haven’t touched on. Arrangers are primarily an amateur keyboard. Don’t all get mad, there’s plenty of us pros that love them too! But by the numbers, I’d say the majority of them end up in the hands of hobbyists and beginners. And if there’s ONE thing that the arranger does that no other backing system can, that is to accommodate players that might throw an accidental extra bar in, or miss a cue and start late. Backing track has no idea what you are doing. But an arranger will happily throw in an extra bar, or an extra bar or two, or jump to the ‘one’ instantly if you accidentally came in in the middle of a bar! They are very forgiving to beginner players…

I like the end results of much of what BIAB does. But at the end of the day, it doesn’t matter one whit what you play the file on! We can debate up and down all day whether it’s an arranger or whether it’s a backing track generator, but the bottom line is, you can’t ‘play’ it. Which makes it moot..!
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An arranger is just a tool. What matters is what you build with it..!