- The stock is already publicly available, so it doesn't go to the company. (However, when you buy someone out, the money you spend to buy other people's stock DOES go to them, which can be dangerous.)
- Stocks can't be sold. It could work, but it just sort of slows down the game without much upside.
- Patents can't be sold or leased. (You do acquire someone's patents when you buy them out...)
- Buildings can't be sold or leased. (You can mutiny them for a period of time to take them over...)