When you release code, you need to do following.
1. Ensure it builds. Old software can only be built with old compilers, with old Windows SDK. Sometimes they also rely on old custom build tools. Other times builds requires manual steps.
2. Ensure you have not violated any copyrights or patents. The relevant laws are ridiculous these days, potentially, you can get in legal trouble even by copy-pasting stuff from stackoverflow.
3. Ideally, that it comes with documentation/comments, at least minimal.
Neither of these are free, they’re quite time consuming. Speaking from experience, I did release a few things, e.g. https://github.com/Const-me/EsentSerialize/
> That way one can trivially look through it
Looking through is not enough. To be sure, you need to build the software and run the binaries you’ve built. Building third-party code, especially old one, can be very hard: dependencies, build environment, mismatched OS versions, and thousand more papercuts. I sometimes spending a whole day just to build some third-party project that I need to use. BTW I’ve been programming for living for couple decades now.
Even if it builds, security audit of a program longer than a couple pages of code is very non-trivial. If you’ll ask “how do you know they are longer than a couple pages?” the answer is “because GUI”. Despite user friendly, GUI usually require substantial amount of code. That’s probably the main reason why open source community is reluctant to create GUI apps despite users obviously prefer them over CLI.