I recall hearing that as well but I can't quite remember what the rest of the picture is - something about the other parts of the immune system being able to do the needed work? Or that it was shown that someone with zero antibodies could still be immune?
Other parts of the immune system, specifically T-cell response. The simplified bottom line is that antibodies provide a quick response that also prevents many cases of mild disease. T-cell immunity lasts longer, appears more universal against variants and should still work relatively well against severe cases.