I mean to be fair there isnt an actual guide based on heroic/mythic DPS. I would be the first to admit when I started I was literally rolling on trash and bosses until I hit a 2 roll or better. Realized eventually and with the help of my buds that doing so was bad. Yes one line in that guide says mythic+ and raid boss dps so it doesnt apply, but some people havent been playing Rogue for very long, if not ever pre Legion, AND have never been one to theory craft or spend time in the Lab to figure this stuff out. So yes if people are following a guide written for raid bosses and dont understand how to pre roll and how to react in certain situations lets call them retards and laugh at their inferior DPS without actually explaining whats wrong.
Edit - The importance of SiW / True Bearing is so large on bosses that spending time pre loading dice rolls on the last 1 or 2 mobs the entire time even if you start the boss with 15 seconds left is so great that I *Highly* recommend doing so. Im not saying to spend the entire time on an aoe pack Rolling dem bones, but DPS one one or two trash mobs can be forfeit to really see Dat Deeps on the boss.