OK, I think I get it now. Making each individual scout it's own little platoon did the job. This is kind of dumb isn't it? Isn't calling in artillery on enemy forces one of the main jobs of a scout?
I'd say it's something to do with old SP radio rules for the (WW2) days when only platoon leaders had reliable access to arty command. Now don't trust me on that...
OTOH, I don't think dedicated FO units have this limitation, so if you want to go out of your way you may replace your scouts with beefed-up FO teams.