RE: Ransomware the end of the 3-2-1 backup?

I do wonder why at home 2 external USB drives aren't enough in your opinion

They are not enough for me, as this does not solve the one off-site backup requirement. It does help with immutability (at least in some degree). As long as at least one backup is offline when your machine gets compromised you are safe. But are you? I worked in IT my entire life, I had my first computer business while I was in High School, and I can't tell you how many times backups are not working when you need to use them. As a consultant, backups were always the last thing on people's mind when buying a server, they were also frequently screwed up in execution.

To set up an immutable backup at home, seems a bit overdone

It depends on your tolerance to loss, and there are cheap ways to do this with as little as two external USB drives. I used to rotate three external USB drives for years, with one going to my parents house each week. With internet speeds the way they are, it is becoming more and more viable to off-site backup everything.

Offsite backup through an online connection is possible indeed (soon and I can get 2GBit/s to upload, ridiculously fast). Still, it is an online more or less permanent connection, which I won't like too much for a proper backup. I learned in my Telco days to unplug whatever is sensitive. That is what I do with my backup USB drive. And soon drives. The one copy (perhaps indeed a 3rd drive of some sort, or the online variant will do I suppose) at another location is indeed something that I need to account for.

For a few years am working in IT myself. My employer has quite an expensive setup for backup with storage rings across the country, two of them. Immutability is possible on both rings. Not too many prospects/customers (including the big boys) don't want to pay for the immutability though—too much storage cost. Well, most companies didn't experience ransomware attacks, is what I can conclude, and CFOs not giving enough money to their CIOs and CTOs.

The old 321 includes a tape as an offline backup. Although a bit old-fashioned, I fully understand this method since this is offline after the tape is taken out of the carousel. My employer decided a few years ago, that this isn't modern enough anymore. Well, I suppose they decided this is too hands-on with a car driving to various data centres every single day to take the tapes and bring them to a large vault. Still today I'm pulled in quite lengthy discussions with prospects who aren't too pleased the tape option isn't there anymore. Fortunately, most of the time I can convince them our current setup is secure enough. Funnily enough, I like my backups to be offline 😆 I guess I can lie well enough about the best solutions and my preferences to my customers-to-be 😆 yes, my 'sales' stories I make quite personal, therefore I feel that I am lying to them 😱