This is a classic management problem. The first person to really get a handle on it was Alfred P. Sloane, who headed GM and wrote "The Concept of the Corporation". He figured out how to organize a very large company effectively, and GM's management structure worked well for half a century. They beat out everybody else until Japanese competition appeared. (GM probably stayed with Sloan's structure too long, but nobody else really knew what to do.)

There's the argument that, rather than one company having a broad range of products, there should be many companies, each with a narrow product range. It's cheaper to run a fund than manage a conglomerate. The conglomerate concept was that "synergy" between the business units would reduce cost. In practice, this rarely works.

There are some successful companies with very broad product lines. Mitsubishi and Samsung are two of the biggest. General Electric was the classic US example, but they've backed off from most of their consumer products other than major appliances.