Users of a library are still users. You can write a library in an ivory tower, just like you can write applications in an ivory tower, but that kind of software

Users of a library are still users. You can write a library in an ivory tower, just like you can write applications in an ivory tower, but that kind of software is written for yourself and only incidentally for anyone else. People might still use it if there are no viable alternatives, but don’t expect them to be very happy about it. Especially because scarcity of communication also implies scarcity of documentation.