The wildly popular, very divisive #boycottNFL Twitter hashtag, explained

Hours after the opening game of the 2016 pro football season, Friday morning's top Twitter trend in the United States was #boycottNFL.

It started out as backlash against players who have lodged silent protests during the national anthem, but was quickly mocked by other Twitter users and co-opted by still others to point out many of the NFL's faults in areas such as player safety.

If we expand the lens another notch, the #boycottNFL hashtag was ultimately one more manifestation of 2016's digitally-fueled culture wars that spring from sources as varied as pro football to movie casting, but so often result in familiar battle lines being drawn.

Before Thursday night's season opener, Denver Broncos linebacker Brandon Marshall took a knee during the national anthem, making him the latest athlete to follow suit after San Francisco 49ers quarterback Colin Kaepernick began doing so in protest of police brutality and racial inequality.

Predictably, Marshall's gesture -- and the rising tide of similar gestures from NFL players -- ticked some people off. And so it was that the #boycottNFL hashtag began bubbling up on Twitter. Here's a sampling of the conversation.

Before long, other Twitter users mocked the commitment of these initial #boycottNFL tweeters, while pointing out other, arguably more justified, reasons one might consider no longer watching football.

Now, would a significant number of people actually boycott the NFL -- for any reason? Ratings for Thursday night's season-opener, a rematch of last season's Super Bowl, were down from the previous two season openers. The game did perform slightly better than the 2013 season-opener, however, so let's not draw any conclusions.

But Marshall taking a knee during the national anthem wasn't the most serious controversy to emanate from Thursday night's game. NFL MVP and Carolina Panthers star quarterback Cam Newton was absolutely rocked, taking numerous shots to the head throughout the contest. Here's a compilation.

Despite Newton's noggin getting blasted repeatedly, only one of those helmet-to-helmet hits was called a penalty. Moreover, Newton was never seen taking a concussion test on the sideline during the game, although the Panthers announced Friday that he passed multiple exams afterward.

It all left many wondering how a league that has professed to take player safety more seriously in recent years could let one of its marquee stars take such a brutal pounding, one that included what appeared to be multiple uncalled penalties.

That -- more than fans up in arms about players exercising their constitutional rights -- is what should really have the attention of league execs as the NFL's opening weekend grinds on.