Why isn't emotional dysregulation its own diagnosable psychiatric condition

Something I keep running into in my work: patients who have significant, consistent trouble regulating their emotions, but no other features of BPD, no anger disorder, no ADHD. Every diagnostic code I reach for is a partial fit at best. BPD has emotional dysregulation as a central feature but requires a whole additional cluster of traits. ADHD lists it as a common presentation but not a criterion. IED is specifically about anger. Curious whether the research community has ever seriously considered a stand-alone category, and what the resistance actually is.