The complexity of truth doesn't fit in a headline, let alone attract enough clicks to win the competition for eyeballs and virality - which means that even if someone somehow succeeded in telling the whole truth in a headline, that article would lose in the race for eyeballs to the clickbait-headline version, which means your eyeballs would (statistically) never see it, and only the clickbait version.

I'd say "welcome to the web" but this was true in 1800s newspapers as well.