yes, that's something Ussop couldn't do
a lookout needs to see for miles across sea. Abs it isn't just people they're looking out for but land, wreckage, etc. Observation haki is not a substitute for a lookout.
a lookout needs to see for miles across sea. Abs it isn't just people they're looking out for but land, wreckage, etc. Observation haki is not a substitute for a lookout.
When Luffy was sneaking into Onigashima, no one could "hear his voice" with Observation Haki.
That also explains how Kaido knew Big Mom lost: once her voice just disappeared, he realized she had stopped fighting, when the only way Big Mom would stop fighting is if she lost, or had destroyed all of her opponents. The fact that her voice disappeared DURING combat is what let Kaido know she had lost, meaning Observation Haki, or at least the versions we've seen, only work if the other person HAS dangerous intent/is fighting.
This is what makes Enel SOOOOOOOOOOO fucking broken for a pre-time-skip opponent, the man could casually sense people just mentioning his name from so fucking far away.
If Enel ever put work into CoA, he would be a true demon to fight.
Same thing with Carrot, to an extent. So many Straw Hats just need Haki to be able to match up to stronger enemies.