There's an important distinction here: if your development team also holds the pager, you're not doing SRE. You're just skimping on sysadmin roles. You're doing

There's an important distinction here: if your development team also holds the pager, you're not doing SRE. You're just skimping on sysadmin roles. You're doing SRE once you field a 12 person team of skilled programmers whose only duty is working on reliability.