Is that they had the ability to hype a crowd to insane levels.
When they released hype songs and performed them,
they were able to make people lose control, scream their asses off or even get chills
yeah other groups had their moments or will have their moments in the future
but this was something that was consistent about BTS
It wasn't just a moment or two
It was them and they were hard to ignore
Regardless of whether they were doing choreo or not
When they started performing in the US
Even without the added angles camera work to make the performance look amazing
They were still capable of putting on a performance.
ANOTHER THING is that even when they were not performing "hype" songs
and had tracks like YOUNG FOREVER for example,
they were capable of making people FEEL every word.