I would say its more down to how they approach the game, as they set themselves up better then Shroud and TenZ do. I mean TenZ at times legit just holds W onto a site and just wins every aim duel. Thats just not how you would play competitively in any way, reason why you wouldn't see any of the players you mentioned do that.
Idk if you would count this as better aim tho, as it is more geared towards pathfinding and gamesense imo.
TenZ and Shroud flick a lot; which is smth you would avoid at all costs if playing in an actual competitive setting, as it is inconsistent and doesnt work as well against better players. I would argue Tenz and such have way superior flicks and raw mechanics just because they rely on it so much to win fights, when compared to someone like Niko who just preaims effectively and as such doesnt need to rely on flicking. That doesnt make Niko bad by any means, as he is just smarter in his approach to the game and less reliant on smth that inherently has a higher margin of failure.
TenZ bad approach to game, but better raw mechanics, due to relying on them, Niko and such way better gam sense and understanding of the game; as a result doesnt need to rely as much on his mechanics, which are still top tier