Information architecture is exactly what its name says it is: The architecture of information.
Trying to tie information architecture with UX or even with design in general is a terribly limiting misconception.
You need good information architecture in systems design, in software development, in creative writing, in system management. You might even need it in developing your creative process!
Information architecture is not a sub-discipline of web development. Information architecture is also not necessarily related to visual design. It is not even as much driven by user habits or established conventions.
What is Information Architecture
Information architecture is simply relevant in any work that needs to communicate information in a way that is understandable and at the same time minimizes other risks that are associated with the communication.
- Written essay needs information architecture.
- The backend of an API endpoint needs information architecture.
If your software lacks information architecture, it will be too chaotic to maintain easily. That will consequently make it less secure than a well-architected code.
If your paper or blog post lacks IA, people will drop out at the start and your message will not go through. If you write it boxed into categories of habit though, it will be too formulaic to be actually taken seriously.
Information architecture is not the routine task of applying a formula, it is the art of finding out the adequate kind and amount of convention.