As a competitor to ADI (and other national distributors), I would like nothing more than to give my canned talking points against such companies and why independent dealers should go out of there way to support independent distributors, but I'll refrain from that and make an objective post based on my own ongoing analysis on this topic.
When you consider national, multiple location distributors, with retail "style" setups, it becomes the "Best Buy" challenge.
On the heels of Circuity City, Comp USA, Tiger Direct and other retail stores closing, Best Buy was getting hurt badly by Amazon, Newegg and other online / eCommerce competitors that didn't have the same overheard as them. To make matters worse, manufacturers were giving these companies the same cost structures as Best Buy. How would best buy go on this way? Certainly they can't afford to offer more value, but make the same or less margins.
Best Buy's value to manufacturers is their many retail locations that afford manufacturers the ability to quickly get their product closer to many consumers, as well as their retail space. Even with drones, or airplanes, this is their advantage over Amazon. What Best Buy was previously not doing a good job of was monetizing their value proposition to their manufacturers. Instead they were trying to "charge more" to cover their additional overhead, and the consumer just simply isn't willing to pay more, ever. Especially once these other larger online retailers became very credible in their minds.
Best Buy realized their value and started focusing on brand initiatives such as "stores" within their stores, gaining free sales labor and collocation style income. Manufacturers understand, that end caps and other marketing exposure don't come free and either the business side will work out with better margin opportunities for the distributor that provides the most value, or directly paying for the value that you want, in a menu style format. It really is 6 in one hand, half dozen in the other. In some cases this is a win win, because the manufacturer can offer the same cost structure to these brick and mortar stores, and then control what additional marketing benefits they get, or choose "D" none of the above if they don't want any. (Although ADI might not be happy about that)
Now back to ADI (as the example distributor), the hope is that they don't just allow any manufacturer off the street the ability to advertise in their flyer, but it is offered to manufacturers that also make business sense for them and their integrator.
The slippery slope becomes, the balancing act between selling marketing to their manufacturers versus selling what makes the most sense for their integrator. This can sometimes create a conflict of interest (similar to what happens with their own brands such as Capture, WBox, Honeywell being sold within ADI versus other manufacturers)
Frankly speaking, I view this more as a strategic way for ADI to monetize their value proposition to manufacturers up front, and minimize their risk long term. Many manufacturers embrace this (even though they complain about it), and view ADI as a marketing portal that increases their brand exposure, as well as a logistics center. ADI competes with the major trade publications in this regard. Manufacturers know that with ADI, they will always have to do the heavy lifting from the technical side. ADI knows that the manufacturer might take on dealers direct, and they would rather monetize their value up front, than take any chances from the sales side of it.
The value proposition for the smaller independent distributors, should be less interest conflict from who is giving them the "marketing support", and more opportunity creation based on the pure benefits for the project at hand. The hope is that the manufacturers see this and protect the independent distributor on such opportunities, but that is a completely separate chapter.