Like when you send a .7z instead of a .zip or .rar to a friend or a teacher because that’s what your computer has installed and they’re like “Oh No, not one of those, now I have to install 7Zip” even though the same program that opens .rar also opens .7z I feel like people are way more annoyed when they receive a .7z
Indeed, I don’t trust those either. As for RAR being “bad”, no I don’t agree with that - but I’ve only ever seen it used in that context. If someone sent me one it would raise an eyebrow, much more so than if someone sent me a .7z file. Likewise if I used it professionally, it would arouse suspicions amongst my peers more than if I used 7zip.
I scan all files already, so nothing new there.
Personally I choose to not deal with RAR and use a format that isn’t proprietary, isn’t patent encumbered, and is FOSS. These are rational, evidence based choices. There are plenty of alternatives that fit my needs better as well as those of my clients and peers.