It's baffling to me that people can't observe the lopsided nature to the synergy of effective strategies in endgame. I've explained it before, several times, but whatever.
It's from lack of clarity by what we mean by relevant content. When I'm talking about what ought to be considered the benchmark, I'm using examples a little higher, like Escha Zi'tah T3, Escha Ru'Aun T3, Reisenjima T2+, the third battle of Sinister Reign, just to name a few. Regular Ambuscade, even on Very Difficult, seems deliberately scaled compared to some to examples and are generally not what I'm talking about. In fact, I'd say Ambuscade is generally very lenient with respect to what jobs are viable.

Melee, for example, might be very viable against most T1 Escha mobs. But that seems like a bit of a weightless consideration when you consider that these are soloable by several jobs.