b) creating a chilling effect which robs the community of momentum on meetups, books, tutorials or even just really enthusiastic fan/technical channels like for example https://www.youtube.com/@NoBoilerplate
If I thought I needed to have a "use of marks" policy at all, I probably wouldn't choose to draft a policy that instead permits absolutely anyone to go around masquerading as The Rust Language, as, well, that would not accomplish any goal.
You don't write a policy like this in such a way that it permits people to use the mark for just anything. It needs to be restrictive, at least a little bit. If it's registered then it needs to be protected; if you allow the indiscriminate use, you lose the trademark (and then just anyone can call their copier a Xerox machine on the package. Now if you're Xerox Corporation you actually do have a problem.)
Then again, I am a Rubyist, so I just went and checked on what trademark policies the Ruby language has, and as it turns out (unless I missed something) there are none. There also isn't a Ruby foundation – there's Ruby Central, the non-profit responsible for organizing the conferences (those are RubyConf and RailsConf) but they don't exert controlling authority over any community outside of the cons. They don't own any trademarks as far as I can tell. Maybe don't need this at all.
There is a Rails Foundation. Another example, not a language but: DHH owns the "Rails" mark and the trademark policy is this extremely reasonable one-pager (that also provides some specific real-world examples of what types of abusive uses it is intended to prevent. It's clear enough to me why we can't have unauthorized "Ruby Rails" dolls for sale by just anyone.)
I don't know how similar Rust Foundation is to Rails Foundation, but if it is too similar then I think I may begin to understand why people do not like it so much. No offense to DHH.
It does feel kind of circular. "Why is there a trademark policy?" Because we have this trademark and we don't want to lose it. "Why do we have a trademark?" To be held in trust by the foundation. Why do we have a foundation? To protect the interests of the community.
Well, if the community seemingly hates this new policy so much, are we doing that?
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There is a third option though, you didn't mention: the Rust Foundation could actually listen to the community's feedback and draft a new proposal. I'm sure they won't let their mark get invalidated. I'm less sure they will listen now. (People all seem to have made up their mind that no compromise is possible, from where I sit.)
But maybe Ruby as a counter-example is more helpful than I thought. What company or collective stewards Ruby on behalf of the Ruby community? There isn't one, at least not officially. I used to think of Heroku as the company. Matz, the language's creator was employed there as "Chief Architect of Ruby" – is he still associated with Heroku/SalesForce now?
I don't know. I tried to find out if that is still true, all I found was a Wiki article that says he works somewhere else today. It's unclear if he still retains the title and position at Heroku/SalesForce.
So maybe Ruby didn't need a foundation, or maybe it did. Look at Heroku now. If Ruby was counting on their support, I think we'd all be in some kind of trouble. Maybe we are in trouble. I don't know how you feel about Ruby, but I like it! And I don't feel in trouble, that's good for me, so maybe I see your point.
I hope that we get to have more cool events where practitioners can meet up and advance the state of the art for their favorite language. And I'm frankly not sure if any of this information makes me more or less interested in using Ruby or Rust today. I think I'm fairly indifferent about it all. I don't want to get sued, mainly.
So I guess I do at least understand "Why CrabLang" then.
a) the trademark getting invalidated
b) creating a chilling effect which robs the community of momentum on meetups, books, tutorials or even just really enthusiastic fan/technical channels like for example https://www.youtube.com/@NoBoilerplate