AFF was popular from 2003-2012. In fact, back around 2007-2008 or so I read a study that said 5% men in the USA had an active profile on AFF. That's not considering all the men that tried the site and then deleted their profile. However, what I noticed about AFF back in those times is it was mostly used by Gay and Bi men. Some of them were open about being Gay, but there were quite a few that pretended to be straight. I'm not Gay or even Bi, but I quickly figured out that a Gay Male could quickly find what he was looking for on AFF. So my opinion of AFF is the site itself was in the closet. It was marketed towards Straight Men, but AFF worked better for Gay or Bi Men and Trans Women.
I prefer Trans Women and back then AFF was the best site on the internet for meeting a Trans. I was on AFF from 2006 to 2011, but eventually I met someone and we agreed to become exclusive.
Eventually that relationship came to an end and I tried AFF again in 2019 through early 2020. Boy... did AFF become a Ghost town. Almost all of the Trans women are gone, except for a handful of Crossdressers. It took a month, but I noticed a lot of the people on AFF were hold-overs from the mid-2000's. AFF has been replaced by Free Apps, Free website, and sites that use GPS to track people.
Anyone that's younger might not know what the online meet market was like throughout most of the 2000's decade. Most sites operated on monthly subscription format. Anyone could sign up for free, but those users were blocked from sending emails unless they paid anywhere from $20-30 a month. Adultfriendfinder still operates this way.