Imagine you ult a reyna and she just waits and blinds when the barriers drop - 90% loss
Same with breach
And like a 70% loss against flash agents, because you have to be prepared for etiher a fake flash or the real thing, meaning that you are kinda disadvantaged
Realistically I see the ult as a counter to shotguns,marshalls, frenzies, stingers, spectres etc. Meaning it could be powerful when you are ecoed playing against a lightbuy or something but that is sich a niche scenario. Addtionally a good use could be ulting the sentinel playing on a given site allowing your teammates to get an easy plant on attack, but all of that depends on how easy it is to ult sb, ( ig you could also try to use it to stall for a defuser, play time, or take a 1v1 in a 1v3 or something but again there are problems wih that ((like what happens when you exit the ult and how are the non-ulted players affected))