I agree with this.
Growing up, I knew theoretically that gay people existed. There were gay characters in books I read and I would occasionally read something about it in the news. But being gay in the tiny town where I grew up "just didn't happen."* After I came out as a lesbian (age 20), I could look back and see the signs, but was completely oblivious at the time. Even after I came out as a lesbian, and I knew trans people existed, it never occurred to me that I may be one. I was happy being a butch lesbian, right..? Like, really butch... And everyone is amused when they are misgendered, right? It just means I'm comfortable in my butchness, right? It took until I met and got to know a transwoman (when I was 30) that I came face to face with what I had really been feeling all those years.
* I've learned in the past few years about 2 other people I went to high school with who have come out. Three may not seem like a lot, but it is a major thing.