It's a regular concert, no more and no less. No over the top intoxication or drug usage, nothing crazy going on during davening, and not even dancing in an impromptu street festival. This doesn't seem any worse than any other concert.
As for the concert per se you
may be right. But it did seem to me that many people at the concert didn't look like they belong there, even if it's just a "plain concert". Just have a look in the audience. This being the situation, you have many unassuming people falling into places they did not intend on, and picking up things they did not go for. You'll definitely agree that this is not what Rosh Hashana is all about.