The simplicity of the interface is what feels novel to me. It probably isn't an issue with a project like Chrome or Firefox to find someone able to understand

The simplicity of the interface is what feels novel to me. It probably isn't an issue with a project like Chrome or Firefox to find someone able to understand all the intricacies of seccomp-bpf and implement it properly. And I am sure seccomp is a much more powerful solution. But for a sole programmer or small team writing some micro-services or similar it seems unlikely they are going to bother. By comparison sending a string with some well chosen categories looks so ridiculously easy it lowers the barriers a lot.