The lowbie doesn't have the comparable attack. The lowbie doesn't have the comparable mez. The lowbie doesn't have the comparable damage mitigation power. The comparable power is 1-5 levels above the lowbie's native level, he/she hasn't gained access to it yet.
The floor hasn't changed. No content was made more difficult to compensate for wider SO availability. No new content with increased difficulty was added in the relevant level range. Nothing is harder because lowbies can use SOs now.
The exemplared character has powers +5 to the exemplared level. Those powers have more slots. Those slots have a wider range of enhancements in them. The exemplared character can use his/her powers more frequently, expends less endurance when using those powers, does more with those powers than the lowbie can. You keep trying to omit these facts, and they are facts, from the equation. You tout a few extra points of damage in the lowbie's attack, and ignore that the exemplared character is using the same attack more frequently. You point to a lowbie mez that lasts a second longer and disregard that the exemplared character's mez's faster recharge time more than compensates for that second. You insist that the lowbie's damage mitigation is better, but don't look at the endurance cost. Over and over again, you focus on one thing, a single number, and proclaim that there should be parity, but utterly refuse to acknowledge the exemplared character's significantly better slotting and larger pool of available powers and how these bring that parity.
The exemplar mechanic isn't going to be improved by making enhancement scaling match SO values, all that would do is make exemplared characters overpowered.