That might have worked for the specific hardware BT needed those developers to manage but it's not good advice in the general sense. Systems Administration is as much a detailed speciality as being a software developer. There's so many edge cases to learn -- particularly when it comes to hardening public facing infrastructure -- that you really should be hiring an experienced sysadmin if you're company is handling any form of user data.

As an aside, this is one of the other reasons company directors like the cloud -- or serverless specifically: it absolves responsibility for hardening host infrastructure. Except it doesn't because you then need to manage AWS IAM policies, cloud watch logs and security groups instead of UNIX user groups, syslog and iptables (to name a few arbitrary examples). But that reality is often not given as part of the cloud migration sales pitch.

True but in BT that was SD's (Security Division) Job to set standards and our teams Sysadmin handled that

SD was the employer Of Bruce Schinner for a few years BTW