current programming language tooling often assumes it can download dependencies from online repositories at build time, and that is not acceptable to Debian.

A secondary benefit is that Debian doesn’t need to rely so much on tools coded by assumers, as it would otherwise. Hell breaks loose once some bloody assumer has power over what you’re doing, because his [often correct, but often incorrect] assumptions will make you waste time fixing shit. That is not just with software, mind you, but everything.

This [no bundled libraries] is not always appreciated by upstream developers, who would prefer to only have to deal with the version of the library they bundle. That’s the version they’ve verified their own software with. This sometimes leads to friction with Debian.

Three important details:

1. Once you release software as open source, you’re allowing other people to edit it.
2. If the software depends on a very, very specific version of a library, odds are that either the software devs or the library devs did something wrong. As such, Debian’s approach would only break things that are already fragile.
3. Debian’s approach actually helps upstream devs to find issues before they become a concern.

The author might mince words, but I don’t. Based on those three details, it’s from my opinion that those upstream devs screeching at Debian, out of entitlement, should suck it up. And that Debian is doing the right thing.