All of our mail servers are properly set up with a SmartHost, SPF, and DMARC. We don't have any reputation issues. That's a 2000s kind of problem.
No, it's current. Microsoft blacklists entire datacenters still. There's a lawsuit in Illinois about it that they lost. It's a very real thing still that RBL are used by the majors (like Microsoft, but not Google) and used to shut down entire ISPs and IP blocks. I've been brought in to help providers with these issues, it's a huge legal problem and if you don't get hit with it, it seems like it doesn't exist, and if you do get hit, it seems like there's no recourse (hint: there isn't.)
We're dealing with a client who has their site hosted in a Yandex.RU data centre and guess what? Yeah, some putz between their web server and ProofPoint has a sinkhole because Ukraine. The web server can e-mail @Outlook.Com because they have servers around the world but not ProofPoint.
We've had lots of issues over the years where one midbone/backbone provider either shapes or blocks packets from another because they're in a contract dispute. Poof. Packets gone.