At the time, it was not at all clear that in-orbit rendezvous would be feasible.  One of the reasons this is so important is that it enabled lunar orbit rendezvous.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Lunar_orbit_rendezvous" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Lunar_orbit_rendezvous</a><p>This drastically reduced the total launch mass for the Apollo missions.