I vote 27 + up, but also know some younger 20-ish skaters would have noticeable improvements in their skating if they didn't skateba board too long or short wheelbase-wise.
I never started caring or even beginning to understand it until I was at least 25. I gotta say, knowing has both hindered and improved my quality of skating on X decks.
Right now I'm on an AH with a 14.25 wb and it's 32" length and it's noticeably shorter than what I've been riding but still works fine. Can do BS big spins really well on these compared to previous decks (that I prefer) where I did them well but more pivot/slide instead of being 100% full like on this deck.
The later the better but only in specific contexts. Can't get too nerdy with people unless they bite the bait and wanna go down the rabbit hole.
Nowadays, I just like for boards from X brands of Y sizes that have 14.25 or 14.5 and I make it work 
tbc, i’m not calling you out here:
i’ve thought this same thing, particularly in the current/just waning milieu of large boards/large wheels, loosey goosey trucks, less pop.
i am a fan of the 90s schoolyard skating, travis stenger beat. seeing the last 10 plus years of large boards that absolutely do help people huck, and go fast, but imo not have the pop on flatground is weird to me.
exacerbating the large setup size, is that a fair amount of skaters are small. when they have a big ass board and 58 mm wheels, and are 5’5” 135….shit looks goofy.
so yeah, sometimes i criticize people’s setup choices, and more so when i see them struggling to do relatively basic flatground.
i struggle with basic flatground, and that’s all i can sorta do. my venture lo’s and 50s probably
aren’t helping me bomb hills, nor skate at even a beginner level on transitions. and that might be helped by using a bigger board.
and shit.
almost every post i make is basically the gear madness thread. mods move my whole personality to the the gear madness thread please.