You are kinda correct on this one, but there are some minor details missing.

Light has a lot of synergy happening in best case scenarios which are coming to show on this very dummy event. Also, until T4 Shingen arrived, a major bonus Light overall had is a insane amount of speed in terms of BG-Generation which no other element had until this point.
The combo of Lugh, Iris, Tish and Michael AW is, although insane glassy, putting up an insane pace and can barrage Bursts and Full Bursts in quick succession.
Light and Dark are also the only 2 elements that get 3 Exceed weapon from UE events while all others only get 2.

Light is a universal element, you may call it neutral, which can perform against any element to a good degree without taking many risks.

In hindsight, this dummy is also the only one were Light has such an exceptional performance. The others to come give other elements an advantage or levels the playfield for multiple at the same time.