Ok, you caught me - I was exaggerating for effect. Nonetheless, this is a real problem for OSX security - I'm happy looking at the md5 to double-check etc etc but my granny? She thinks the internet has gone down when she gets a popup because "I can't get on to Yoohoo" (which means in granny-speak: this window is obscuring my web-based mail client).
Remember, OSX is mainstream now. And mainstream is not sourceforge/github/aptitude/macports
You must be terrified by all things in general.
Hint: there's an easy fix for that. Search for people reviews on that download service or app ;)