There is a slight imbalance the other way by the chassidim because slightly more boys are born than girls. As they age, however, the “extra” boys die off (e.g., according to the Israeli census the extra boys are gone by their mid-thirties).
Therefore, imposing an age-gap by chassidim – to ensure that there are an equal number of people ENTERING shidduchim (e.g., 19 year old boys and 18 year old girls) – would result that 35-year-old Almanos and Gerushos would have a harder time finding a shidduch.