+1. In the classical period (1995-2005) being an enterprise DBA was pretty hard. You had to know your OS inside out, you had to understand how to do fast I/O and then you had to design the database, as in tune how tables should be laid out for maximal performance. Wasnae easy, cap'n.
Hear hear. I miss those days. You really ended up knowing the systems, both hardware and OS, better than most of the sysadmins.
Oracle tries to be clever and decide things for you. It does acceptably for most of the time. But not always. And being Oracle is buggy as hell. And it can get it really horribly wrong. It is also even worse piece of bloated crap than what it used to be.
All-flash or tiered is cheap so that takes care of I/O performance. Of course raw blocks weren't just for performance, it was also to bypass filesystem cache, after all you cache rows in memory anyway, but also for ensuring that writes that the database thinks have been written to disk have actually been written to disk.
Having said all that, even if everything is faster and more automatic, the data volumes and business requirements have increased too so there is still very much need for skilled DBAs. Don't forget lusers have not improved even if hardware and software may have done.