My very first arranger (a Roland RA90 module) was initially bought ONLY for the drums section. I was playing with duos and trios with drum machines (mostly Yamaha and Alesis) and feeling very musically constricted by having to program the entire song in advance or else you have one pattern for the whole song (!), and the arranger's two patterns and two fills you could trigger with a simple footswitch was a huge boon.

Fast forward to today, and now I have four patterns, six fills, breaks, intros, count-offs and endings, and synced audio loops, and drums so realistic many ask me what drummer I recorded! I think back to those simpler days... Nah! I think I like it better today!
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An arranger is just a tool. What matters is what you build with it..!