Interesting view, and perhaps contains some truth somewhere. I think your point of view is from tyhe bottom up, where you're experiencing the road kill experience as an innocent rodent crossing the road, looking up as a consulting vehicle imprints its Michelin treads on your face. I've experiences this too, but I've also experienced it from the top down, and from the middle, in the guds of the beast, so to speak. Most companies need help with specific problems and questions which they can't address with the in-house talent they already possess. This is because those people are already oversubscribed with corporate noise they call a full time job, leaving them with no realistic bandwidth to go tackle that interesting question or problem or project.

Consulting companies unofficially have A-grade to C-grade talent, because larget boring companies can only be given the C-grade people and the A-graders are so lite they'll only work on extremely advanced and juicy projects or they'll quit and go work for the competition. That's why when viewed from the bottom, these consulting firms appear to be 99% idiot zones.