SOAD had the advantage of absurd humor that could actually be funny ("Pogostick" for example) and where always (outside of their drummer nowadays) unapologetically left wing in their politics.* The album "Toxicity" came out a week before 9/11, and still feels relevant as it tackles such themes as the industrial prison system and police brutality, while also predicting the fear and paranoia of a post 9/11 world. I wouldn't call it or them Nu Metal, but it does feel like the ultimate "the bubble has burst" album. After that and the events which followed, there's no going back.
I did a relisten to SOAD over the Summer and I was surprised at how well it all aged. The Zappa type tendencies on their first two albums really shine through in the lyrics. "Prison System" still has a ton of bite with the lyrics remaining as relevant as ever. They also are much heavier than any actual Nu-Metal band besides Slipknot. There are sections on their self titled that almost go thrash metal and Serj does some death growls on that album as well. System does start to get a little troubling on the double album because for some reason Daron Malakian got a big head and tried to share or take over Serj's vocal duties. On Hypnotize more than half the songs are sung by Daron. Daron is a solid backup vocalist, but it's like if Stevie Van Zandt tried to sing half of the songs on a Bruce album. Serj's vocals is one of the main reasons System stood out and were so unique. Daron's voice is whiny and awful on songs like Old School Hollywood, Violent Pornography, and Lonely Day which almost had a Emoish tone to them and was so much better on Toxicity where he would just be in the background.
I will say also there are a couple Slipknot songs from All Hope Is Gone and Volume 3: The Subliminal Verses that I like and they have a few songs I think are pretty close to actual Heavy Metal. Some sections straight up sound like death metal until the vocals kick in. Their self titled album is still pretty obnoxious and dated, but they definitely have some talented people in the band even if the music they are making isn't my favorite.
From reading interviews, Corey Taylor from Slipknot is straight up progressive and has talked about that while he supported Bernie, Dems need to unite to get Trump out like a year ago. It's weird to see someone associated with Nu-Metal seem so with it and most of what I've read from him when discussing politics have been right on. Also, the Papa Roach singer Jacoby Shaddix dislikes what Trump is doing to the country and has spoke out against him.