There’s a pretty straightforward solution to this problem which is to run your own NPM server even if it’s only a caching proxy. For some orgs, the uptime provided by the third party servers is sufficient.
Having been at 3 companies that did this, I can say with certainty that our caching proxies (artifactory in all of them) were much more likely to go down than the public repos were.
Yes, but at least in that case you have the fallback of the public repos.
Yeah, I think I've lost a day in total when our local npm was finicky on several occasions or failed to fetch latest version of a package that we've developed in house, but made publicly available.
They just don't have to be down at the same time to be useful.
Maybe it's obvious and straightforward enough that other people have come up with the same idea, tried it and not found it to be worth the effort?