The guy who drove Sears into the ground also did the classic private-equity self-dealing to carve off all the valuable bits and saddle the company with debt. Berkshire Hathaway is an example of a company that owns lots of businesses which are mostly independent

I’d theorize it has something to do with whether the separation actually makes sense. Berkshire Hathaway owns separate businesses that have zero to do with each other and may spin off or bring in new ones anytime. Sears had different departments of the same store trying to beggar each other which is counterproductive.