The whole POSIX standard is outdated, especially in terms of safety and security. With all experience and knowledge gained during last two decades, it's time to make a new standard, with better thought APIs, better friendliness to non-C languages (e.g. Rust, C++, etc).
I think of standards as coming in two flavors, declarative(this is how things should be done) and descriptive(this is how things are currently done). posix is mostly on the descriptive side of things. that being said posix is a prime example of the duality of standards, it is both a terrible standard, encodifying things that probably should not have been encodified and vitally important, it keeps everybody on the same page. On that note I consider posix a good starting point but it is no great sin to abandon it when needed.
These days posix is largely "how does linux do it" just like in the past where it was "how does insert_large_unix_vendor_here do it"
