Decisions about what? The low-hanging-fruit software companies have already been built; the most successful new software companies are all about a specific vertical, and this requires specialization.

Trivially, yes it would be best to be 100% expert in programming, 100% expert in marketing, 100% expert in business, and 100% expert in whatever the business domain is, but that isn't feasible. That's why most new start ups have a founding team, not a founding superperson.