Not being exposed and thus made aware of such attitudes can leave you in a bubble and not realize how good you have it. I didn't really realize how many people in the world have attitudes that belong to a 150 years ago in the developed world until I traveled to such places and saw and interacted with it with my own eyes.
It just seems that Reddit’s filtering mechanisms are not really adept at dealing with it anymore. And Reddit’s demography (white, cis male, hetero†) adds a very special and unique slant to all of this.
† Hey, I’m all those things, too. Hanging around with only those people isn’t very fun, though.
In any english website, your going to mostly encounter english (which means probably white) cis hetero people. Gays and transgendered people are %10 of the population at most, and a lot of times, they're not talking about things related to their sexuality.