Poppy isn't off meta. It's just that nobody plays her right.
Grasp of the Undying and
.
Poppy is a bruiser, dammit. Here are my gripes with the way I see others play her:
Poppy's passive is not an offensive tool for aery procs. It's arguably one of the best trading tools in the game, especially with Grasp, but people just use it for free poke.
Poppy's ultimate, even pre-8.10 HAD DUELING POTENTIAL. Her snapcast ult was always labeled as a "make or break" "0 vs 200 IQ" sort of deal that's only in the game to screw up your team's combos. The hitbox is absolutely disgusting, and you can use it to catch up to people who think they're out of your range. Also, the fact that the ability as a whole was labeled as pure utility for knocking away carries sort of pisses me off--being able to remove an unstoppable front line to get to the carries is sometimes a better use for a Poppy ult.
Poppy is set apart, as a tank, from others due to her lack of AOE cc, so she can't do much in teamfights outside of her ult. However, as a bruiser, her single target damage and cc are amazing, yet she still has good survivability.
By all means, prove me wrong. I'm just a Bronze Poppy main who had a few good games and hates the meta. I just really don't see downsides to this playstyle, even at higher level.