I got a kick out of part that "IT" contributed: infrastructure and security. I would argue your entire company is IT, with exception of certain back office jobs like A/P, accounting, etc.
Whether you realize it or not, much of that entire project falls under IT, from any traditional definition in a manufacturing type environment. When you are a tech company, I don't think it redefines what IT is. Just means the "business" employees are extremely tech savvy, maybe even having Comp Sci backgrounds.
For example, I'm a developer at small business unit. I have to manage the entire spectrum of a project like that. I probably would have asked 3rd party experts to assist with security and infrastructure stuff at the scale you are operating. But that doesn't make them "IT" and me not.