This makes me suspect there might be some very specific mechanic in mind behind how the WoL works (I don't think it's just the Echo at this point) and it allows for ridiculous strength but also very deliberate and particular limits. Idk if it'll happen, but wouldn't be surprised if Shadowbringers examined the limits and nature of the WoL more. Devs seem to be allowing a lot of room for expansion and this is a really fun question that I wouldn't expect them to pass up.
That's the Blessing Of Light. That's why we had to collect 6 crystals in ARR. Originally it was our plot armor to protect us from things like Ultima and the Ascians, but over time it's grown into this deus ex machina type power that lets us do whatever the plot needs us to do.