I’m responding cross-thread because I think this fits better here and I would like Survey: Use cases for shards' `postinstall` to be focused on describing use cases, not judging them.
I strongly object to this. Requiring a bunch of dependencies even just for installing the sources of a dependency is quite demanding. It forces every user to have Ruby and rake available. Even if they don’t need them or their product (the mruby/ruby libraries). For example if the C libraries are already available, there’s no need to built them. Or if there no intention to actually build the code that links these libraries, there’s also no need to build them.
I understand the motivation to package everything conveniently, but I think this is not really developer friendly. You are forced into a specific workflow and the only way to opt out is to skip postinstall entirely.