I do recall google apparently stopped using raid in some data centres, but it was because they had whole-machine redundancy.

RAID is probably redundant for some of the uses it used to have, like optimising read performance by using many drives (SSD is fast) and honestly I suspect that SSDs are probably more reliable as they don't have a bunch of platters and bearings and screaming rotational speeds.

So if you needed it for a base level of reliability, an SSD on its own may have exceeded that.

I suspect there are still uses for drive redundancy in some high availability setups.. although your friend might be right. If the likelihood of drive failure is lower than other parts in the machine and you need high redundancy for availability it might make more sense to replicate the whole machine rather than the drives.

It's possible redundancy specifically for the drives was an artifact of unreliable drives back in the day 🤔 they might have a point! I think it's likely still useful at times though.

I'd rather hotswap a drive than set up a new server, even if it's a less likely scenario.