ADHD is a neurodevelopmental disorder, either you're born with it or you're not. Sure, lots of things fight for our attention and that probably affects us in some way, but distractability isn't the same thing as ADHD. It's primarily a regulation disorder rather than 'can't focus disease'. Where I think you bring up a good point in a mechanism that probably reveals ADHD in some people, I would definitely give pushback on what appears to be a suggestion that the advertising industry as it exists causes ADHD. I don't think any serious psychological professional would make that assertion.