Tiggy never said her point of view is the only one, and actually she suggested something that would accommodate people on both sides of the issue quite nicely. The person she replied to wants level syncs with no regard to whether or not other players want it that way. *shrugs*
Just... what? The fact that someone has good gear and can roll through a dungeon automatically means they are lording their gear over others and mocking them? I mean, did you stop to think that some of us enjoy helping lower geared players get through content more quickly? Did you stop to think that some new players may not take seeing someone that outgears the content as "omfg why do I play this game" but rather see it as "omfg I want to be like that person someday" and be inspired to work their little tails off to gear up? The great part about this game is there is no P2W aspect. Everyone can get the same level of gear. You may not be able to get your class' optimized gear without raiding, but you can still get some pretty damn good equipment just by capping tomes every week.
The problem with saying "never sully your hand with such old content again" is that SE keeps sending us back to that old content over and over in order to help newer players get through it. Low level roulette sends us back to anything under level 50. Animus sends us back to low level dungeons too. Zodiac primarily sends us to level 50+ dungeons (with two exceptions, Dzemael Darkhold and Aurum Vale, both of which are high level and have long waits in the queue because people dislike them). Without veterans being sent back through the content, newbies would have a terribly hard time getting through the dungeons they need to progress their story quest. They'd be stuck facing either long queues or looking desperately for a party. Many would probably lose interest and simply quit.
Long story short, if you level sync the 50+ dungeons too low, you make them take way longer than they have to which impacts the queue times for other players. You also make it less likely that people with higher-end gear will actually go run them unless they are absolutely forced to. Hell, if the dungeons were 40+ minutes apiece due to level sync, I probably wouldn't be working on my 3rd Zodiac weapon. That's one less tank or healer in the queue (god knows I don't queue as DPS unless I'm in a premade cause that queue time is murder, seriously), which means two more potential newbie DPS waiting that much longer to get into a dungeon that they need for progression.
I guess you also missed the part where she suggested an optional level sync. *shrugs*Clearly, since it's obviously all about you and your gear, and you care nothing about anything else.