I didn’t coin the term and I too believe it’s a huge generalization. However, “simpler” people are more susceptible to ads. The “normies” in question are the ones that don’t use adblockers, they believe ads are normal and they believe ads don’t affect them. Corporations capitalize on that. Better tech education would definitely help take some power away from corporations.
Edit: even now you’ll find people that use Lemmy apps that have ads. The bigger the user base, the more greedy companies will find ways of exploiting the Fediverse.