Counter points, based on experience:

1. Yes, if you have an application that works this way you will have to manage your deployment to compensate. But you can use configuration as feature flags to keep a monolith but when you deploy it to X servers you enable one feature set and to Y servers you enable another. So you get the benefits of developing in a monolith but the isolation of microservices.

2. See #1, but also use proper error handling. It's been a while since I've seen a single request take down the whole app.