Whereas if this conversation was about something with broader stewardship, like _Linux_, I'd be saying this is silly, you shouldn't be compromising other things just so you can build your RPi kernel on an RPi.
> In OpenBSD there is a strict requirement that base builds base. So we cannot replace any base utility, unless the toolchain to build it is in the base.
> Such ecosystems come with incredible costs.
Basically, the cost of adding rust to the OpenBSD base system currently far outweights the proposed benefits (reimplement fileutils), especially considering people will probably not want to pour in the effort needed to rewrite those with strict POSIX compliance (which is another requirement).
He's not saying rust isn't useful but that it wouldn't be a net benefit to have a hard dependency on it in the base system. In the BSD world folks take a very strict and conservative view of what can go in base (and for good reason IMHO).
This is different from the GP comments about just making it possible to use rust programs/libraries in OpenBSD, so we're definitely on a tangent here.