Well, that was fun
Ironically, they were young when they started playing. The idea that D&D wasn't directed towards and mainly played by young adults is hilarious. It still is; it's not D&D's fault that people age.Here's the sad truth: this isn't a new war. It's a new front in a war that's possibly older than the hobby itself.
Gatekeepers gatekeep for a reason; they don't want certain types of people in their hobby (or certainly not being welcomed and catered to, at the very least). Stream fans are, by and large, a younger, much more diverse audience (regardless of how true this actually is, it's hard to deny that this is the most common perception of that audience). And grognards lamenting younger, more diverse D&D players is about as old as dirt.
Honestly this whole thing has much more in common with the whole chainmail bikini thing or even gamergate than with any edition war.