Well, that is simply not true at all.
Go is a perfectly capable replacement for Java and C#. Many huge projects that would likely never be written in Python have been written in Go when they would have otherwise been written in Java or C# in years past: Kubernetes, Prometheus, HashiCorp Vault and Terraform, etcd, CoreDNS, TiDB, Loki, InfluxDB, NATS, Docker, Caddy, Gitea, Drone CI, Faktory, etc. The list goes on and on.
What, exactly, are you saying that Go can't do that Java can?
Go is not a perfectly capable replacement for Rust, for example, because Rust offers extremely low level control over all resource usage, making it much easier to use for situations where you need every last ounce of performance, but neither C# nor Java offer the capabilities Rust offers either.
I like C# just fine (Java... not so much), but your comment makes no sense. Certainly, I would rather use Go than most scripting languages; having static types and great performance makes a lot of tasks easier. But that doesn't mean Go is somehow less capable than Java or C#... it is a great alternative to both. If someone needs more than Go can provide, they're going to rewrite in Rust, C++, or C, not Java or C#.