> most abandon programming proper rapidly - I'd hazard within 3 years - and
  > go on to other tertiary fields (PM, DevOps, SRE, etc)

SRE is a specialized subfield of programming. Someone has to write and debug all those low-level tools (runc, systemd, etcd) that sit "below" what most people consider to be the backend stack.

If someone becomes an SRE because they don't like programming, they're going to be in for a big surprise when they discover how much quality time they're about to share with the unshare(2) manpage.