See, unlike some other more advanced, contemporary operating systems like VMS, Unix (and early versions of POSIX) did not support async I/O; only nonblocking I/O. Furthermore, it assumed that disk-based I/O was "fast" (I/O operations could always be completed, or fail, in a reasonably brief period of time, because if the disks weren't connected and working you had much bigger problems than the failure of one process) and network-based or piped I/O was "slow" (operations could take arbitrarily long or even fail completely altogether after a long wait); so nonblocking I/O was not supported for file system access in the general case. Well, when you mount your file system over a network, you get the characteristics of "slow" I/O with the lack of nonblocking support of "fast" I/O.
A sibling comment mentions that FreeBSD has some clever workarounds for this. And of course it's largely not a concern for modern software because Linux has io_uring and even the POSIX standard library has async I/O primitives (which few seem to use) these days.
And this is one of those things that VMS (and Windows NT) got right, right from the jump, with I/O completion ports,
But issues like this, and the unfortunate proliferation of the C programming language, underscore the price we've paid as a result of the Unix developers' decision to build an OS that was easy and fun to hack, rather than one that encouraged correctness of the solutions built on top of it.