So, I went and watched his Arcane Trickster video, and it's not clear how he calculated the baseline. Using his methods, I get a 20th level baseline of 53.9 damage. This is sneak attack, rapier, GFB on a single target, with advantage. The build has tools like sentinel and the possibility of triggering GFB or BB secondary damage, but I can't fit those in (I made a few guesses) and get to his numbers. I will say it's close if I just assume BB with secondary damage, at 66.5, but that's not quite the number on the sheet. I double checked my sheet against his baseline damage, and I can recreated that perfectly, so the count is right. (He also has an error in his baseline video for a 1st level warlock using EB and Hex in that he doesn't add the Hex die to the crit damage, so it's a tad low in the video).
AT can get much higher damage -- one case of upcast shadow blade in dim light, getting an off-turn sneak attack in, and using warcaster to maintain BB (and the rider on BB triggering both times) is around 150 damage. That's nice. I just cannot align whatever unstated assumptions generate the chart posted -- there's something there, but I can't tell what. Baseline using the method is much lower, so clearly there's some assumption of getting in more damage. I'm more than 10 points off the line at 20th.
Your earlier outburst is misplaced. The argument was that rogues need advantage to keep up, and this actually shows this. Whatever additional assumptions are made for the AT, constant advantage is included as a requirement. Without it, the build isn't as impressive (although still good versus baseline). I am not trying to discredit the comparison, but understand it, something I still can't do. I get that it's super easy just to not care about how these things work and assume it's good enough for you, especially when it's making your point, but a failure of understanding leads to being caught short when something doesn't actually work out. And pointing to someone on the net as an authority not to be questioned is just poor all around. If you can't do the work, just own it -- no big -- but don't mock people trying to understand how the work was done. You can be bigger than that.