Most of the FOSS community is hostile to even creating basic sandboxing. The Flatpak project gets panned all the time. Not for having a weak sandbox (which would be a fair criticism), but for having a sandbox at all and not using 90s-style package management.

A lot of people from the FOSS community seem to believe that (at least from recurring discussions) that Linux is secure because the software is open source and you can trust the maintainers. The idea that even trusted software can have vulnerabilities and that the 80s/90s security model of the standard Linux desktop means that you are only one Mastodon/e-mail/RSS/whatever client vulnerability away from exfiltration of your whole home directory does not even occur to them. All the while all these applications use (XML/image/...) parsers from the 90/00s written in C.

The only reason we don't see mass-exfiltration of data is because the Linux desktop marketshare is effectively meaningless. Though we see some results of the desktop security disaster (also to some extend of macOS) through leaked credentials obtained by compromised NPM, PyPI, etc. packages.