The SPLC suffers from the same conceit much of the Left suffers:
We're all basically progressive, from our vantage point in the coastal cities, and it's a small minority of rednecks who are getting in the way of our agenda.
We all have degrees, here LET ME SHOW YOU IT, and "no one in academia" takes anything but the progressive agenda seriously, and it's basically a CONSPIRACY led by the Kochs and other industries because rich people never have principles and all they care about is money. (See also: "Dumb-ass NRA members, all they do is shill for gun manufacturers who want your money." Translation: I wish you guys would stop giving money to the NRA because they're wiping the walls with us and if I insult you enough maybe you'll switch sides like my spineless friends do whenever I call them out for being transphobic or whatever.), and
Government and bureaucracy is the great aegis behind we in the civil rights movement do our thing. Government good, individuals bad. Government trustworthy, people not so much.
The SPLC does not understand - nor does most of the Left - their own culpability in winding the loudest and most aggressive of the Right up. They do not understand that their constant canvassing for bigger and more intrusive government (their guys with guns), winds up and radicalizes the right (the aforementioned bad white guys with guns liberals "sometimes see when they're summering out in the 'country.'")
They are also engaged in a propaganda campaign to "un-cool" the opposition. The Left is terrified of disapproval of their peers, and are endlessly making the point that they believe the right, socially acceptable, politically correct things. They do not quite grasp the fact that this is mainly their trip and while there is also pressure and conformity on the right, of the two extremes, someone on the right is more likely to tell his compatriots to go fuck themselves if they don't respect his dissenting view.
I am on all of the SPLC's lists, and they mainly talk to themselves (fellow travelers), and this is evident by the way they write. They do not understand conservatives, gun owners, patriot types, people who are really interested in being southerners, evangelicals, and so on. For them, this is one big inscrutable blob into which they stick anyone who uses certain keywords.
Unfortunately, many of the groups the SPLC calls out deserve to be called out as dangerous or hateful. But by lumping in anyone whose language makes them uncomfortable into this blob, they discredit themselves. I can post a fully factual report on some subject from the SPLC and I will get a torrent of responses saying, essentially, "Didn't read it, SPLC bullshit."
The other thing about the SPLC is they survive largely on the "progressives pure of heart, conservatives driven only by money and hate" sanctimoniousness of their donors.
How much money do you suppose the SPLC has? The SPLC mainly fights a civil rights case against this white nationalist cartoon or another, and has a website.
What would you guess?
281 million dollars.
The SPLC has made Morris Dees a rich man.