Indeed, there's nothing to be gained from denying it. They could have kept totally quiet, and everyone would just assume 'that's what spy agencies do'. A denial, especially in these very strong terms, never happens.

It wasn't infinitely bad for James Clapper to have lied under oath about NSA's data collection. It wasn't infinitely bad for the US to have been caught spying on Merkel. Etc. etc.

Everybody spies on everybody, everybody accuses everybody, everybody lies about both, gets caught and mostly doesn't care. The allegations prove just as much as the denials - nothing. Eventually one side will be caught lying, and nothing will happen to them.

It's possible for broken clocks to be right every once in a while, depending on the type of clock.

Like if Donald Trump said "to most people in our area right now, the sky appears blue", he would probably be right, despite his general propensity for lying and manipulating other topics