Granted,

At least the ServletContainerInitializer shouldn't fail a deployment (throw an Exception) when it can't find parts of the deployed application that it needs to run.

Most SCI's that we've come across rely on the @HandlesTypes discovery to make this determination.
if the foundClasses set is empty on onStartup(Set<Class<?>> foundClasses, ServletContext context), the SCI itself assumes that there is nothing to do, and simply returns (skips) its own execution.