That's not correct. The latest npm (and any npm configured with ca="") will use the CA baked into your operating system's version of OpenSSL. Our old cert, from GlobalSign, works just fine with OpenSSL.
But moving to our new, self-owned cert in a way that broke anything was avoidable, and a huge error on our part.
Additionally, what are your thoughts on signing the digicert CA with the npm CA as mentioned here [1], thus fixing old clients and avoiding another cert switch?
https://github.com/npm/npmconf/commit/d7ef61c8d9ae87f39482c5...
I believe we considered adding the npmCA and dismissed it, but it has been a long week and I can no longer recall why. I will bring it up and post an update here next week.