Company command I can see making an ADSO, because let's face it almost every officer wants to be a company commander, and we had such a hard time retaining O3s back during the GWOT that we were offering them all kinds of incentives to stay in. We were so short on majors that we were double-BZing captains to O4. Getting captains to stay in until major often meant that they would be careerists.
Battalion anad brigade command... fewer people want those jobs, and they're hard. It's also fraught with things that can get you into trouble. It's stressful. If you know you're terminal at O6, and brigade command is hard as hell, why take the ADSO when you could have a sweet offramp job, do SkilLBridge, and then start your O6 retired pay earlier?