The most overrated speaking advice is to never say “Thank you for your attention!”
It will ruin your talk, the advice goes, because
- it’s boring (at least not energising)
- it’s disrespectful to the audience because you can’t be sure they actually paid attention (although great speakers usually can)
- there are much stronger ways to close your talk (which there are)
The advice is (mostly) valid. It makes for some great anecdotes about bad talks everyone can relate to.
And it has close to zero effect.
I have yet to see any talk where that closing line makes or breaks the talk.
If it does break your talk, you almost certainly have much bigger problems than that line.
Ditch that line. But also, don’t waste your time with the unimportant stuff.