You're not really going to know a living person who will make a cultural footprint because we are living it, we won't notice the impact on future generations.
Posters suggesting generic manufactured pop bands such as Spice Girls, Spears are just saying what has been an impact for them personally, it's not wrong but they won't be remembered for anything in another 50 years.
It's the same kind of principal where I could say Frankie Knuckles, Larry Levan because they was instrumental in the early days of electronic dance music, Tony wilson and New Order for essentially bringing it to the UK to forment the UK scene which became a global export.
NWA, Public Enemy has had a bigger cultural impact despite the likes of Sugarhill Gang and Grandmaster flash being 10 years senior, same with Nirvana hitting the mainstream.
All have a common theme, they all was a figure head of the youth fighting back against the world that was accepted because the media machine realised it would pay money, Elvis had his gyrating hips and danger of Rock and Roll, Beatles was phsocelic, NWA/Public enemy was championing ganag violence, Dance scene was listening to car alarms and kids dying from "cake", Nirvana was depressive shut ins.
People younger than me will cite many artists that will make an impact, it is down to the media to reflect on what does, but that has been somewhat slanted, not so much now with the internet but it does play into a lot of recent popular culture.