The problem is that you are trying to make sense of an organization(s) that never makes logical decisions and/or is ruled by back-door deals and corruption (Bernie Ecclestone, 2019 Ferrari Engine, Red Bull essentially having 2 teams, etc.). Andretti & Cadillac/GM, who excel in Indy, WEC, NASCAR, etc., are globally known brands and also would bring a bigger audience from The US. The only reason they do not approve this is that it somehow lessens the payout over the next several years to current stakeholders and team managers. The only 11th team they would approve is someone who comes in and over pays and then further grease palms with backroom payoffs. No different than FIFA, Olympics, etc.
F1 is in a position to really take off on every continent. Instead of further inclusion for long term health they throw more sprint races and road courses. A few more seasons of not only non-competitive championships, but the abundance of street courses that do not allow for passing and entertaining races is going to hurt the sport.