Ovinomancer
No flips for you!
Very true, it is not the end of the world. And I already know about the designer's intent on 5e - both what you stated, "rulings over rules", and the like... though I still think that with those in mind it doesn't imply they meant the help action to be constituted as an attack (that's RAI again mind you, nothing wrong with you ruling otherwise as a DM). And your post does clarify your intent, as I genuinely didn't know if you were fighting for a RAI argument or not.
What are you helping with? An attack? Okay, you help make an attack.
The bits about feinting, or yelling, or whatever are fluff. What you do is help your ally make an attack.
As for the dragon, I'm with [MENTION=6801845]Oofta[/MENTION] on being a bit shocked that someone would rather say 'but the rules don't explicitly call it an attack and there's no attack roll so it's not an attack' rather than go with the obvious results of 'well, yeah, of course it's an attack.' I can see the former, but I just don't get the mindset that would rather be hidebound to their interpretation of the rules and create this strange chimera of rule interactions rather than get to the obvious, common sense result. I'd have done that in my formative years, when I thought the rules were intentional and good and without the possibility of mistakes, but now? Nope, and I don't understand arguing over multiple pages trying to get someone else to explain why they wouldn't play hidebound to rules that create nonsense.
By all means, play your way, but were I a player in a game where a dragon used it's breath weapons and stayed invisible because it wasn't an attack, I'd pack up and leave. Not because that issue was unacceptable, but because the mindset it reveals isn't something I want to deal with anymore.