So, uh, rollerblading. I had this thought out of the blue so I thought I would chip in my own 2 cents (or 5 due to the penny being retired).
I associate rollerblading as the cooler rollerskating, given that you had to essentially balance on two moving rails and be wary of your momentum. There also wasn't a nose brake at the front so you had to do some interesting stuff to slow down. There was a heel brake, but I used a T-Stop method variation, or rather the Pstar slide as it's called in the present day. I also fell sideways alot because my thick head didn't think to try and derby slide out when I did. Truly the biggest rollerposer on this side of the world.
(Much like Skate culture, some of the trick names are cryptic as to why they're called the names that they are. If you're part of that community, that's some money sitting around, go do some research!)
I played a lot of Aggressive Inline for the PS2, way more than one should play btw, I am almost done 100%-ing a second character. I blame the interest in aggressive inlining to Insetik47's Rolling Let's play, the fact that it was European only only added more forbidden fruit factor. This isn't going to be an in-depth culture exploration, lord knows how amateur and unprofessional my lens into the aggressive inline period would've gotten. I was just curious about why this period had real X-Games footy, and why there was this general aggression about peeps that blade. I probably did a remark about the X Games removing Rollerblading, until I remember that the chance that I would care about some ESPN sport coverage would be the exact same if it was still on.
My guess is that doing some parkouring acrobatics looks more funny than cool, which is strange to think when there's guys full on spinning wicked fast on a vert surface with no helmets sometimes. Sponsoring might be hard to spot, which is easier when displayed on something like a skateboard deck or an entire BMX setup. This was also the time where anything that the public cool cats didn't like would've been called 'hella gay 80's style' or something even more negatively charged. As a skateboarder that grimaces when somebody taket their Ebike to the skate park, I would imagine it would be like navigating the ocean. Move past the school of 7 year olds on their scooter, avoid the apex predator of the BMXers, and then right before you go to practice your trick, a rabid Blader would appear out of nowhere and body you. The pathing of all of these different transports would look like trying to draw inside the lines with your non-dominant foot, of course there's going to be grouping.
Coupled with the fact that you would normally see either people at a roller rink with wheels on their feet, or kids trying to go around their cul-de-sac, and the image of rollerblading outdoors with the intent of getting sick tricks seems goofy. With the advent of trying to make any dumb thing into an extreme version of itself, like the Flowboard as I somehow managed to stumble across, the value of maintaining what's in and what's not becomes more valuable.
Honorable mention goes to heelys, which I do have a pair of, I keep thinking of them as high platforms with how gigantic the shoes are. There was a point in time where I was curious to see if anyone invented tricks for Heelys, and I'd wager it's a mix of parkour and rollerblading. There are those who attach grindplates to them in an attempt to make a lovechild of SOAP shoes and Heelys, but at that point you might as well just switch to a rollerblade at that point.
Also, there's a Heelys YT channel that joined in 2009 and has crusty vids of doing vert tricks. Also there's a heelys forum?!? I need to focus on heelys on another page, I got some sleeping to do, but jeez did that pique my curiosity.