Agreed that outsourcing risk does not free you from the responsibilities. However, for many many services you have to rely on others to provide the service better than you could do yourself, as you are limited in time, money and other resources. For running production grade databases at startups, it's much more cost-efficient to run on AWS RDS than to hire a systems engineering team with 24/7 standby. For more trivial systems you might be right and managers might be cowards. However, you have to realize it's a spectrum.

Whether you're running it yourself or you outsource it, things will go wrong at some time. When this happens, and you run it yourself, you also have to explain why it went wrong in a post-mortem or RCA. The problem is that your customers have no point of reference for your explanation (how likely is it that this occurs again?). In my experience, the following message goes down a lot smoother: "This is an Azure/AWS/GCP outage which affected not just us, but 1000s of other companies. We rely on {provider} to continuously learn from their mistakes and improve their service and they've shown this in the past. Here's their post-mortem report about this outage.". Note that not all cloud providers fit this bill.