I've seen this done first-hand a few times. In every case that I can recall, it was not due to a manufacturer wanting to cut a partner out of a deal, but because the end-user was an anomaly and more or less insisted on a direct purchase arrangement. In one such case the end-user was a large federal entity that did ALL of their own installation, service, etc. They had several techs that were trained and certified on the products they used, and otherwise were as competent as an average integrator.
In many cases "normal" integrators did not even want the pass-through sale, they viewed the moderate margin (6-8 points on a $150,000 deal) not worth the future risk of having to offer some sort of warranty support or otherwise getting caught in the middle of a deal they had no control over. I did not really blame them for taking that approach.
For my experiences, integrators did not really care when this happened, because they recognized they had no shot at the business themselves anyway. They were not invited to bid, they were not consulted along the way for product demos, comparisons, etc. The end user was never going to come back later and ask them for a labor-only or service-only bid, so in the end they did not see it as anti-channel because they were never going to get that order anyway.
On the flip side, if there was a case where the end-user was one that would have normally bought through a traditional channel and the manufacturer orchestrated one these "obfuscation sales", then they would get understandably upset.