That being said, the on-call sucks. It's really awful, and something I've never seen before. It's also typically the primary cause of team churn for people in my org. This varies, as I've seen other teams stacked with L6 engineers with very little churn (4-8 years of tenure each). This is very much a pit of despair of our own making, but I still haven't figured out how teams like mine get out of it. My own view is that normalization of deviance means that engineers who've only worked at AWS just accept that getting paged many times in a week at awful hours for false positives is OK.
There's certainly a view that the only way to get promoted (which is incredibly difficult) is to create new features or products. You read this of many orgs though, not just AWS. I'm not convinced it's fair to single out AWS. It can be endemic in some teams, and I've certainly worked with engineers who are clearly only focused on shining for promotion.
The worst I've seen was a team go from 8 engineers with > 2+ yrs tenure down to 4 people with < 6 months, over the course of a couple of months. This was for an enormous product. That team had a very tough 4th quarter.
AWS does handle operations failure incredibly well. If you've hopped on a LSE call before, the execution to identify, mitigate and review correction of error (COE) is world class. Doc / design review is also very thorough.
There's ample opportunity to learn a lot during your time at AWS, and many engineers have carved out incredible careers in this place. Just go in with your eyes wide open.