Maybe I'm looking more at myself since I turned 40, but I'm wondering what traits led me to become a grognard?
1) Not using projectors for maps at the game table
2) Backing off from 4E to play Pathfinder a decade ago
3) Backing off from 5E to play 4E currently (haha)
4) Not following Critical Role
5) Not active on Discord or Reddit but preferring message boards like ENWorld
6) Using miniatures and tactical combat over "theater of the mind"
7) Not using D&D Beyond
8) Not getting into Virtual Tabletops like Fantasy Grounds or Roll 20
9) Using dice instead of die rolling apps
10) Not liking people using PDFs at the table (preferring physical copies)
I find myself wondering kind of the same thing. I'm not sure I'm a grognard, but I do know I'm quite set in more than a few of my ways when it comes to tabletop gaming.
I'm almost a decade younger than you, so I find myself wondering WHY I'm not in touch with things like Critical Role, not on top of things like Reddit or Discord, not "streaming" (I'm still a little baffled by the idea that a lot of young people are watching
other people play D&D for fun, D&D is not a spectator sport in my mind, it's fun to do, not to watch.) I still live in the fond hope of doing the Ds&Ds for a living, it's the only thing I know how to do professionally and my physical & mental health problems make it hard to hold down a real job, so it's quite a disadvantage that I'm such a late adopter of these crucial marketing channels.
I've never had an interest in using D&D Beyond or Virtual Tabletops. I'm pretty positive that doesn't make one a grognard. I'm entirely sure that using real physical dice has nothing to do with being a grognard. I hate pseudo-RNGs and dice rolling apps.
Using projection maps on the game table has nothing to do with being of the Old Guard or not, I think: personally, I just don't have the technology, or the motivation to seek it out and implement it, for that kind of production values.
Anyway, I would only play 3.5 until last year, when I tried Pathfinder. I was going to be content with Pathfinder but lost the friends I was playing, so the only reason I finally came around to D&D 5E FIVE YEARS after it was released was that it's all anyone in my area was playing. I was pleasantly surprised that it was really good.