Yes, meetings are necessary for a plethora of reasons and sponsorship is definitely necessary to present the programme and iron out errors in its application.
However, much of AA has become a programme of seeking refuge in meetings and cuddling up to grandpa-sponsor, therapist-sponsor, or chum-chum-sponsor to rake over the vomit rather than living the solution.
The solution involves a lot of action and a lot of independently seeking to build a relationship with God.
Sometimes, meetings and sponsorship are so effective in providing relief that the individual who meets and is sponsored never recovers because they never have to face themselves and they never have to take responsibility for rooting out their defects, cultivating virtues, and relying on God.
The book refers to self-reliance in two ways: firstly, the Marlboro-man independence of the materialistic prideful person (page 68) and secondly to the brimming-over variety of a person who has established a firm relationship with God (Doctor's Opinion).
A little more of the second variety wouldn't go amiss.