It's not as cut and dried as that, really. I mean, the gender ratio isn't split 50:50 between male and female for many Pokemon, so it might simply be for many that they don't actually find any female Pokemon to use...when it's 75% male and 25% female, good luck finding a female of that species. People will base their choice in Pokemon on nature, ability, and IVs as well; if those all match up to what they want on a male Pokemon, it's kinda logical that they'd use that instead of finding a female equivalent.
Plus...personal preference? There are some who want all-male teams, and others who want all-female teams, and some who want a mix, or specific Pokemon to be male or female. A lot of factors go into making a team, it's not just "I don't want female Pokemon because they're useless" or something...at least, I've never seen someone say that, and mechanically it's incorrect anyway, because gender has no effect on stats. It's not BAD to have an all-male team because that's what you want. It's not bad to complain about being hit by Attract status a lot if you make that choice, either. Attract, like all status effects, is irritating. Whitney's Miltank is notoriously obnoxious, that's just another nail in the coffin on top of Rollout and, in the Gen IV remakes, Milk Drink.
If you're seeing a few people who are acting the way you're describing...well, they're not common.