All true. But recall reading Chariots for apollo, Chaitin and MSFC history, when NASA had to offer compromises to von Braun. Why? Because he (ahem, his team) was the one who did the launcher, had no significant competition in the heavyweight category. Others would dally, blow up engines (like Kuznetsov in the USSR) or be afraid of switching to cryo when it mattered. With more incumbents, NASA hq and politicos in D.C. would be reluctant to support von Braun.