[phillmv]

If I had to guess, I would wager it's because it's expensive and hard. Plus there's the fortunate coincidence that - as far as I recall - rubygems has mostly Just Worked Fine, Thank You Very Much™ .

(I miss the days from when github also hosted a gem repository…)

Solving the authenticity problem alone is probably not fun – tho obviously there is much to be learned from CPAN. Given recent problems there will probably be enough political will to make this happen in the future, though.