Can you explain exactly what that library using Tokio internally exposes to you that's a problem? Because, as written, this sounds like a religious argument.
If you need to use (for the sake of the example) Rusoto, since it is based on tokio, you'll need to set up the Tokio executor or at least add a macro to your main for this to be done for you. I believe Rusoto actually would take care of this for you if you haven't done it yourself however friction arises when you were already using a different version of tokio and Rusoto is built against another.
Basically, it isn't entirely opaque to you how it is handled.
