That's exactly why you don't want to use those features, for what it's worth.
logging
security hardening
firewalls
backups (both point in time and complete backups, both for database and for any other artifacts like image uploads)
testing backup recovery (both the point in time and complete backups)
replication
HA
LB
SSL termination
postgresql configuration
monitoring (security, system stats, application availability, individual process running)
performance analysis (both at application and system level)
method for deploying updates (to the application and to the system)
and the list goes on... you could easily make a career out of focusing on postgresql configuration, for example. these aren't simple things to do.
Different providers have different limitations on what you can do here. For example, AWS doesn't support multicast, which limits your options for doing High Availability.
It's not an insurmountable barrier, for sure. Knowing how to operate your own code is a great feeling.
B) A multihomed setup is not a black box of mystery, and is nowhere near as expensive as people are saying from the hip.
Then "you," having acquired years of experience in designing and implementing distributed services, are making at least a 6-figure investment in opportunity cost.
Almost all of the things you outlined are things that have in the past blown up in real world deployments, often at cloud hosting providers where you didn't know about it it because a well-paid, well-trained ops team hid the drama for you.
So yeah, definitely factor that in to the cost of hosting at a cloud provider. You're absolutely right.