Define hard here? Because there is a lot of bookkeeping involved, and, yes, to get some of the effects you have in Erlang that are necessary for reliability, you'd basically have to create your own runtime atop Go. I.e., yes, if you just want to "if this process fails, restart it", you can do that trivially in another language, but "if this process fails -kill these others and restart them from a known good state-" is devilishly hard, given that Go has no way to kill a running goroutine. You can send a message along a channel of "hey, you should stop", but if code execution in that goroutine never gets there, you have no guarantees.
And while the CPU doesn't have special instructions, the VM -does-. Exit signals are guaranteed in the language spec; a colocated supervisor is guaranteed to be able to both detect a failed process, and to be able to kill others. Go offers no such tooling, let alone such guarantees. I'd be quite interested if you say you did that; I suspect it was, as mentioned, just "hey, if an error comes out of this response channel, restart the goroutine". Possibly also a "here's a channel we can send 'kill' commands on, downstream goroutines should check it occasionally to see if they should terminate". A lot of bookkeeping, no guarantees.
I think you're making a mistake a lot of Erlang/BEAM/etc. (let me call it just Erlang after this) advocates make, which is to conflate Erlang's solutions to problems with the only solutions to problems. Almost no software is written in a language that has the ability to actively kill running threads externally. This is not a catastrophic problem that causes the rest of us to routinely break down in tears; it is a thing that occasionally causes bugs, merely one on a long list of such things. On the scale of problems I have, this isn't even in my top 50. When systems are written with that understanding, it's only a minor roadbump. So the fact that I don't have Erlang's exact solution to that problem isn't even remotely worth me switching (back) to Erlang for.
Is it a problem? Yes, absolutely. Is it a problem worth spending extremely valuable language design budget on? Heck no, and the fact that Erlang does is a negative to me, because what they gave up to get that capability is way more important to me.
Does my solution exactly match Erlang? No. Of course not. But it gets me 90% of what I care about for 10% of the effort, and in the meantime I get the other things that directly impact my job on a minute-by-minute basis, like an even halfway decent type system (it's not like Go's is some sort of masterpiece here, but it's much better than BEAM's), which Erlang sacrificed as part of its original plan. I understand why they have the type system they have, and what they got out of it, and I'd rather have a decent static type system and solve those problems another way, which happens to be the conclusion pretty much everyone else has come to as well. Again, genius thinking in the 1990s, way ahead of everyone else, don't let my current assessment of Erlang diminish the fact I deeply respect what it did in its time... but not a solution I have much interest in in 2021.
Define hard here? Because there is a lot of bookkeeping involved, and, yes, to get some of the effects you have in Erlang that are necessary for reliability, you'd basically have to create your own runtime atop Go. I.e., yes, if you just want to "if this process fails, restart it", you can do that trivially in another language, but "if this process fails -kill these others and restart them from a known good state-" is devilishly hard, given that Go has no way to kill a running goroutine. You can send a message along a channel of "hey, you should stop", but if code execution in that goroutine never gets there, you have no guarantees.
And while the CPU doesn't have special instructions, the VM -does-. Exit signals are guaranteed in the language spec; a colocated supervisor is guaranteed to be able to both detect a failed process, and to be able to kill others. Go offers no such tooling, let alone such guarantees. I'd be quite interested if you say you did that; I suspect it was, as mentioned, just "hey, if an error comes out of this response channel, restart the goroutine". Possibly also a "here's a channel we can send 'kill' commands on, downstream goroutines should check it occasionally to see if they should terminate". A lot of bookkeeping, no guarantees.