all of that is correct and also basically what i said. the reason it became a big deal was because of accessibility. the definition of a "long press" is short enough that older users, who tend to hold the mouse button down for longer after a click, were suddenly seeing popup windows everywhere and, believing it to be an issue of the site they were on, assumed their popup blocker was broken. the timing was adjusted to one second in an update and also the long press shortcut was made optional.

when it was pointed out to mozilla that having a popup containing one big blue button in a popup with fancy graphics around it might also be harking back to the popup ads of yore, and that it might compel people to click on the only visible button on instinct, their head of firefox did an interview with pc world where he countered this with, and i'm paraphrasing here, "nuh-uh". this was in reference to an ama they did where several interaction experts weighed in with frankly pretty standard stuff: don't surprise the user, don't shove things in their face, don't draw attention needlessly.