OK, this is an almost philosophical discussion about what innovation is, where and how it happens, and so on.

My personal impression after more than 10 years in consulting:

• Disruptive innovation certainly doesn't happen in consulting firms. For a number of reasons: a) it destroys their client base and disruptors are not filling the revenue gap the disrupted are leaving. b) The search for disruptive innovation inevitably means risk and failure, which both are not really well regarded in consulting and by their clients. You hire McKinsey to get a solution that works, not a moonshot
• Incremental innovation: Consulting firms are quite good, however, at quickly picking up innovative things (either created in-house or in universities or other countries etc.) in established fields and bringing those to market, thus driving innovation within their client base. This is certainly true for processes and methods, but also in other fields.

Hope this helps

Elias