Considering the popularity of Gaming Grandma, I think it's just the stereotypes. Until recently, even social media was a nerd thing that brought out thoughts of smelly social rejects not respecting social spaces.
The internet is only just now not for social rejects, gaming being labeled for kids and something you outgrow seems to be an individual choice brought on ( often as I see) to peer pressure to stop in the first place.
I'd say there's not a cut off, people just have some really shit opinions about things they should just stfu about. I grew up in the South and I abandoned trying to follow the minds of judgemental folks a long time ago. Half the time they're just jealous you live your life and they haven't managed to keep their personality after getting married and having kids. π