Andretti weren't accepted just because other teams don't want to get another competitor and share prize money with them. After all, this team have long history in multiple racing series and they would come to F1 with bigger ambitions than Haas for example.
Isn't it because it wouldn't be that much of a competition for them? As a whole? Like not so much experience and wouldn't add value to the F1 since they are more into the IndyCar series and races? The drivers are particularly supportive of adding more competitors but maybe the F1 management is not agreeing with it. Maybe in the 2028 season?