That's right genius. They SHOULD be ignored, as their rating system far more often than not fails to make valid observations of a player. Yet people (like you apparently) continue to buy into it just because. How many Rating services are out there for the NFL? Where else would people go if they wanted that kind of information? Of course it's popular when they have little to no competition.

And because people want to feel like they know everything, they accept what they read without bothering to actually watch the player in question and see if he really lives up to his PFF ranking.

Name me 1 example of how you think it fails to make a valid observation...

I suggest you read this: https://www.profootballfocus.com/about/grading/

Focus on this section:
"How subjective is the Grading?

Many people say that as soon as you start grading, you bring subjectivity into your work. Obviously, to some degree, that’s true.

However, there’s also subjectivity around whether a play was a QB run for negative yardage or a sack, if an assist on a tackle should be awarded and if a catch was dropped or not. Sure, you can come up with a set of rules to determine which is which, but in the end, at the borderline between one and the other, it’s always subjective. It comes down to a judgment call.

The real trick of grading is to define a clear set of rules, encompassing each type of play. If your rules are thorough and precise enough, the answers just fall out. It becomes as easy as determining the dropped pass that hit the TE right between the numbers.

Statistics in their raw form are considered objective. But in our opinion, with the small number of NFL games played each season, raw stats are very often unintelligent. If a QB throws three interceptions in a game but one came from a dropped pass, another from a WR running a poor route and a third on a Hail Mary at the end of the half, it skews his stats by far too great an amount to be useful. Our grading allows us to bring some intelligence to the raw numbers and with many different sets of eyes getting a look at each game, we’re able to avoid the individual biases that may arise if only one person was responsible for grading the game."

Except for the players and coaches who endorse PFF for how accurate they are.

What players or coaches would that be? Coaches have their own grades, and I'm sure any player who ranks high on a list will praise it, and those who rank low will say it's wrong. That's not a legitimate judgement, in my opinion.

Wisniewski signing a 1 year 2,5M contract with the Jags?!

There must be something wrong with the guy to have so many teams pass on him and to eventually sign for that little.

I would've thought at that price he would've provided some nice depth at the interior of the O-line.