Not as much as it used to be, actually - I have a book on the subject with regards to girls who play baseball today and they’re growing in numbers. There’s even a women’s professional league in Japan these days which draws fans male and female alike!
Throughout the history of the game, there have also been women who played in men’s leagues, and in the 1940s and 50s, the AAGPBL existed, filling the void left when male players went to fight in WWII and Korea. There were women’s barnstorming teams in the first half of the 20th century. Bob Hope formed women’s baseball teams on at least two occasions (as if we all needed another reason to love Bob Hope, right?). There have been quite a few women team owners and coaches, as well. And to top it all off, Take Me Out To The Ball Game was written about a female fan, Katie Casey, and her unbridled passion for the game.
Baseball may look like an exclusive boys’ club at first glance, but ever since Title IX allowed girls to play, that’s been changing (there are more girls in Little League programs now than ever before). Women, once very much included in baseball, are fighting their way back in after being excluded from the game for some time.
On a side note, softball wasn’t originally created to shove women into. Softball was a version of baseball created to be played indoors and was initially played, like baseball, by everybody. As time went on and American men became threatened by women’s success at baseball (see Jackie Mitchell for my favorite example of a badass female ballplayer), society began forcing them into softball more and more frequently until Title IX allowed them to once again play whatever sport they wanted under protection of the law.
…sorry that this became an essay, but this is one of those subjects I know way too much about. (I even did a project on it as a senior in college.)