For a recent project we developed our application atop Akka.Net (a C# implementation of an actor system) We had a great experience with it despite the architectural learning curve.
Serverless or function apps seem to be quite popular at the moment. But in my mind they appear to be simply a specialised case of the actor model. I've not used serverless in production, but at a glance, actor systems seem to win in terms of flexibility, theoretical
soundness and maturity of tooling. In contrast I've heard horror stories about the kinds of hacks developers who've embraced function apps have made in order to squeeze out decent performance.
A compelling argument in favour of function apps appears to be: cost, hosted services providing an easy means to scale out and relatedly, platform buy in from AWS, Azure, et al. But equally I could easily imagine a PaaS version of an actor system which could share the same attributes.
Is it the language that actor systems are couched in? What makes "serverless" more compelling?