So why can't the module developer choose to change the url if they want to introduce breaking changes?
Why is this built into the module system and triggered by a v2? I don't think there is a compelling reason to do so, and there are several compelling reasons not to do so.
I think I prefer the status quo where there is very strong pressure to remain backwards compatible if your module is used by a few people. This leads to far less churn in the ecosystem and more stable modules.
The article makes the assumption that a major version number is used only for breaking changes, but many software packages use such version numbers for major feature releases (as indeed Go2 seems to plan to when/if they release it). I'm not clear why they should be forced to adopt urls ending in /v2 as well.
I guess you are getting in to Go design philosophy. These questions are similar to "why go does not allow lint to just issue warning for unused variables / packages instead of giving hard compiler error?" The answers to these are unfortunately unsatisfactory, no matter how logical.
Reasonable thing is to use language which align your philosophy.
I've used Go for almost a decade and am pretty happy with it, including the rule you mention. It's fine to disagree with decisions made, it may or may not be heeded, but if no-one ever disagrees the language would be poorer for that IMO.
A module developer _can_ change the URL if the want to introduce a breaking change. Absolutely no problem here. But they do not _have_ to: Adding the version as v2, v3, ... to the module name works also. Nobody is "forced to adopt urls ending in /v2". Go modules work pretty well, are very flexible but seem to differ too much from what people are used to and nobody really seems to read all the available documentation and descriptions of why that way and not how language X does it.
As I understand it importers are forced to use urls ending in /v2 for imports, and to find out which major version a project is on when they do import, please do correct me if wrong.
I'd rather this was a choice made by package maintainers individually rather than the go tooling. Most packages simply don't need that as they strive to be backwards compatible and never introduce large breaking changes. Should they always be relegated to versions like 1.9343.234234, because the go tool requires it?
Honestly, yes. According to semver, a major version change is for when you make breaking api changes. If a project is backwards compatible, it wouldn’t need to increment the major version.
Why is this built into the module system and triggered by a v2? I don't think there is a compelling reason to do so, and there are several compelling reasons not to do so.
I think I prefer the status quo where there is very strong pressure to remain backwards compatible if your module is used by a few people. This leads to far less churn in the ecosystem and more stable modules.
The article makes the assumption that a major version number is used only for breaking changes, but many software packages use such version numbers for major feature releases (as indeed Go2 seems to plan to when/if they release it). I'm not clear why they should be forced to adopt urls ending in /v2 as well.