sadly, i don't recall ever saying that aggressive skating was harder than skateboarding. quite frankly, aggressive rollerblading is 10 times more dangerous than skateboarding because of the bigger drops and higher rails. while skateboarders can drop significantly large distance, there is not debate that aggressive skaters can gain more speed, therefore dropping longer stairs sets and so on. also, aggressive skaters hit higher ledges and rails than any skateboarder could ever dream of doing. while skateboarding exhibits flat ground tricks, along with grinds, aggressive skating is oriented mostly on grinds, with drops and spins as a lesser practiced trick variety. there is no doubt in my mind that aggressive skating is much more dangerous and scary than skateboarding, however i do not believe that either one is "more difficult" than the other.
your argument is invalid as well, because I have never skateboarded. i have used a longboard for transportation purposes and did not find the basics of riding a skateboard/longboard to be difficult at all, so you also cannot claim that i'm biased because i've never been on a skateboard.
that being said, some may argue that due to the increased risks of aggressive skating, it is, in fact, more difficult than skateboarding. quite frankly, the average height of most grindable features in skateboarding is 1 feet to 2 feet off the ground. 1.5 feet is about the lowest feature any aggressive skater would use, and even so, it would be solely for practicing new grinds. my final point, grinds to drops are nearly unseen in the world of skateboarding, yet they are a standard type of trick in aggressive skateboarding, along with other non skateboarding tricks like wallrides and switch up grinds.
