The ratcheting hiring bar[1] and the punishing promo process[2] mean that SDE II has to be treated as a career role as a practical matter for the tech orgs to continue to function. As hard as it is to retain good engineers, it'd be even harder to retain good managers if they were expected to manage all their SDE II's up or out.
[1] - Every new hire is expected to be better than 50% of the current employees in a given role and level across the company. This means the "bar" for a given role and level continuously trends higher modulo attrition.
[2] - Senior engineer candidates typically require at least a dozen peers and managers at or above the senior level to each dedicate a couple of hours to write detailed SBI feedback. The promo candidate's manager then has to spend many more hours crafting a lengthy document from this. The doc then gets reviewed (i.e. picked apart) multiple times at every management tier up to the org VP. At any point along the way it may be punted back for rework, or denied. The process gets even more cumbersome going to principal - so much so that it's often said that the easiest path from senior SDE is to leave Amazon for a couple of years and get hired back as a principal.
source: former Amazonian who really liked working at Amazon, but who finally got an offer elsewhere he couldn't refuse.
The ratcheting hiring bar[1] and the punishing promo process[2] mean that SDE II has to be treated as a career role as a practical matter for the tech orgs to continue to function. As hard as it is to retain good engineers, it'd be even harder to retain good managers if they were expected to manage all their SDE II's up or out.
[1] - Every new hire is expected to be better than 50% of the current employees in a given role and level across the company. This means the "bar" for a given role and level continuously trends higher modulo attrition.
[2] - Senior engineer candidates typically require at least a dozen peers and managers at or above the senior level to each dedicate a couple of hours to write detailed SBI feedback. The promo candidate's manager then has to spend many more hours crafting a lengthy document from this. The doc then gets reviewed (i.e. picked apart) multiple times at every management tier up to the org VP. At any point along the way it may be punted back for rework, or denied. The process gets even more cumbersome going to principal - so much so that it's often said that the easiest path from senior SDE is to leave Amazon for a couple of years and get hired back as a principal.
source: former Amazonian who really liked working at Amazon, but who finally got an offer elsewhere he couldn't refuse.