When we first designed Zendesk, we had ITIL compliance as a bullet point. We're children of the ITIL era and speak ITIL natively. But when explaining the ITIL complex to IT people outside of the IT management world, we quickly realized that we weren't aiming for ITIL compliance but rather ITIL inherent.
In the current market, labels such as ITIL Compliant, ITIL Verified or ITIL Ready clings to help desk- and ITSM products like bees to honey, implying that these products will support all requirements your ITIL processes will demand. But products that claim their ability to support all ITIL processes are breaking one of the key principles of good product design: you can't be good at everything. The ITIL processes may very well be in family and tightly connected, but that doesn't mean that one tool fits all family members.
Aside the basic Service Desk function and the Incident Management process, 9 out of 10 organizations have close-to-none experience with ITIL processes. And the concept of best practices not to mention compliance to best practices on a field with such limited presence, is almost a contradiction of terms. Best practices are based on repeatable procedures that not only have proven themselves over time but also for a large numbers of organizations.
When explaining the concept of e.g. Change- and Release Management to somebody from outside the IT Management world, you quickly realize that these processes are much closer related to traditional project management than they are to Incident Management. Thus, implying that you can cover an organizations change management requirements with a help desk tool, is a vast exaggeration. At best, you use your help desk to establish the link between Incident-, (Problem-) and Change Management.
We take great pride in not claiming any kind of ITIL compliance. We're ITIL natives and couldnt dream of building a help desk without speaking ITIL. If you plan to implement wall-to-wall ITIL processes and are looking for a tool, we say "Good luck to you, Bank of America, now go see Cap Gemini or IBM. Its their core competence, not yours".