I'm actually curious now if the 30 year old boomer meme is in any way an outgrowth of the Iraq war. The aesthetic the meme embraces reminds me a lot of the guys I knew my age and older who served. Gonna have to reflect on this a bit.
Personally, I think the 30 year old boomer meme is rooted more in the fact that internet culture moves so fast these days that anything even a few years old is considered dated. Combine that with the definite cultural differences between Millennials and Gen Z, and the boomer meme makes sense.