Interesting that this is basically the same point as a comment on another submission last week from the same blog:
https://news.ycombinator.com/item?id=27386666> But they never made this complaint in the actual Bugzilla where someone could consider their feedback, they skipped straight to the "complain via blog post" phase. [...] My advice to the author is that perhaps they should extend a little more charity and "just ask" first, before they jump at the opportunity to complain in public - without having mentioned the issue to anyone with the ability to fix it.
Which comment links in turn to another post, for which the blogger writes,
> I would file a bug report but I cannot imagine that Fedora would accept it. They already know that this feature doesn't work; it's right there in the DKMS manpage. It's there anyway because, well, I don't know. This is the most user-hostile decision I think I've ever seen Fedora make.
but in fact the issue was fixed within a week of reporting it.
Firefox, in particular, uses the not-so-secret escape switch to unlock Rust nightly features on Rust stable. A bunch of folks on the Rust team are pretty unhappy about this (see e.g. https://github.com/rust-lang/cargo/issues/6627), but it is the current situation. So "Firefox broke after I ran rustup" is a very different complaint from "My code, on Rust stable, without the secret escape switch broke after I ran rustup," and the blame (if there is any blame at all, which is unclear without the actual error report) is on the Firefox developers, not the Rust developers.
In the general case, the Rust folks care a lot about backwards compatibility, but in turn they do that with an eye towards never having a Rust 2.0. They've taken a lot of innovative steps towards making Rust 1.x usable indefinitely, including the nightly/unstable system, the epoch system, crater, etc. A consequence of staying on Rust 1.x indefinitely is that you cannot possibly be bug-for-bug compatible with Rust 1.0 and Cargo 1.0 for all theoretically possible code (see Hyrum's Law: https://www.hyrumslaw.com/). However, if something breaks in the real world, report it, and I expect the Rust developers will be sympathetic and try to fix it. Without any indication of what broke, nobody can do anything with this post except get unactionably mad at other people, and that's pretty useless for actually getting things done.
The author is, of course, free to blog whatever he likes. But I think the HN community should stop upvoting his clickbait posts.