Ok, so when you say "no file system should be doing random writes", you should make it clear that you're not trying to describe file systems that actually exist

Ok, so when you say "no file system should be doing random writes", you should make it clear that you're not trying to describe file systems that actually exist in any sort of production-ready state. I would generally agree with a statement that new filesystems should be designed to avoid random writes except to solid state media. But for users wanting to deploy a real filesystem now to commodity hardware, the recommendation has to be "avoid SMR", not "use a smarter FS and tiered storage hardware".