While I agree a FF alliance would add value to their frequent flyers, it is not a necessity to attract business travelers. If your business is primarily in the Midwestern United States the biggest factor is going to be convenient scheduling for where you need to go. Not every business traveler works for a multinational organization.
I agree 100%. While F9 can't provide DL or UA-sized networks, membership in Sky Team or Star would, IMO, generate more business as customers could still earn the benefits of a major alliance by flying F9, or fly DL or UA when the route they need isn't served by F9. Since F9 can't offer the benefits of a major FF program, I'm curious how many pax (business and leisure) choose another carrier even though they may prefer F9's service.
I've been building status with UA this year. When I can't fly them, it's nice to continue earning EQMs flying US or CO. Ultimately, I fly UA more often because of the choices provided by the greater Star Alliance.