Maryland state comptroller and Takoma Park resident Peter Franchot advocates for the end of Montgomery County's alcohol monopoly in a Washington Post op-ed. He claims that the monopoly doesn't financially benefit the county and is an idiosyncratic anachronism in the state of Maryland. I'm not sure that I agree with the former (and the piece doesn't really present much evidence or analysis to support the claim), but the magnitude of any financial benefit would be small and could be easily offset by increased fees elsewhere. After all, every other county in Maryland makes due without any increased profits from a monopoly. And Franchot does not advocate immediately dismantling the county's alcohol distribution and retail system, even though it's not clear why the county would want to compete with private companies in the trade.
I think that the best argument for dismantling the monopoly and distribution network and retail stores is that the county has no need to be directly involved in the business of selling alcohol. Let private enterprises do that and let Montgomery County do what it loves to do - regulate and tax.
Oh, and grocery stores should be allowed to sell beer and wine, but my understanding is that this restriction is a state one and is not unique to Montgomery County.