I think 'hate' really represent the mind of some people (even if they are a minority) but even if we ignore this extreme, the level of irrationality in technical discussions is generally quite high. You need to have rational people to have a rational discussion. The sad reality is that a lot of technical discussions are only superficially rational and are often a political play to assert superiority on other people (it's true for languages, frameworks, code editors, methodologies, etc ... ).
Meanwhile the Firefox rewrite, the premium example of what they propose is still plodding along and Mozilla PR blogs aside, Firefox is still plugging vulnerabilities in each release and will be for the foreseeable future.
Now let's look at the Swift community... do we have blog posts from them every week about how awesome Swift is and why one should rewrite their working C and C++ code in Swift? No, they keep doing their thing, Swift is becoming better at cross platform, it's also getting some support for machine learning.
That's how one grows a language, through building successful projects, staying positive (and having an entire platform behind it). Not through doomsday scenarios and a constant barrage of criticism.
This is exactly what the Rust community is doing! RIIR is something that's only really insisted on for relatively small pieces of security-critical code. With huge codebases like Firefox the rewrite is done piecemeal, to put the rewritten code in use as quickly as possible. The "doomsday scenario" talk about memory-unsafe languages does not come from people writing Rust, it mostly comes from the security community, even at places like Microsoft - because guess what, they've literally been running around with their hair on fire for decades, and they're sick of this especially now that something like Rust is available!
FWIW, I use C++, not Rust or Swift, and I have a fair amount of knowledge and experience vested in it, but I think these questions are worth asking.