I think you're underestimating the diversity of environments out there. Not everyone's using cutting-edge deployment tech; lots of folks are just SSHing or RDPing into a physical or virtual server, copying stuff there, and running it. Certainly, that's how things were done at my last job. And it can get worse; some of these environments are locked down in some way or another, by security policies that limit what you can do. In those environments, having the executable be fully self-contained is really helpful.

(For the record, I am a proponent of things like containerization and serverless, and generally try to bring them into use wherever I can. This doesn't require me to ignore the reality that lots of places don't use them, and that this will remain true for a long time to come.)