Why is W at a maximum at equilibrium

[Ernie Lee 3F]

Hello, I just wanted additional explanation on why W is a maximum at equilibrium. For instance, HA + H20 -> H30+ + A- where HA is a weak acid.
Is it because as the reaction is most "stable" at equilibrium, we have more options for positions? However, wouldn't there still have to be a certain ratio of HA to A-? Also, when 2 molecules of HA "swap" positions, does that count as an additional state?

[Chem_Mod]

This is a result of the 2nd Law of Thermodynamics. A spontaneous change results in an overall increase in entropy of the system and its surroundings. Entropy is greatest when a thermodynamic macrostate is comprised of the greatest number of microstates (most disorder). The macrostate with the greatest number of microstates is called the equilibrium macrostate and, there, time-independent thermodynamic variables remain constant.