For those new to the concept, they would pay for a portion of your advertising, you, the integrator would pay the remaining portion.
Well, technically the integrator would pay both portions. That advertising money doesn't come for free, it typically comes from profits, which are driven by margins. Sure, in some startups the money initially comes from investors, but you still need to maintain respectable product margins.
These kinds of arrangements are mush less common today, as you noted. I think that as some product categories have commoditized and prices have dropped, there is less room left to do this.
At VideoIQ I had one customer in particular who was a big Honeywell dealer at the time. Honeywell would give him 60% off MSRP, while I would only give him 30 off. Honeywell would give him a $10,000 sponsorship for a tradeshow booth while I would only give him $1000. For a while he thought Honeywell was doing him a favor until he really started to look at what things *should* cost, and not just the discounts off inflated MSRP (related: Legal Attack on MSRP - Impact on Hikvision, Sony, Pelco, More).
Many of the larger manufacturers will still offer some kind of co-marketing dollars or help with local/specialized trade shows, but it's lower numbers and less common than it was at one time. Account managers are often measured on gross margins of their accounts. They can give you extra steep discounts, or lots of marketing dollars, but typically not both.
IMO, getting lots of marketing money is "bad" in the same way getting a tax refund is bad. If you're a larger account and you're getting lots of marketing sponsorship, you're probably not getting the best discount on your regular orders. You didn't do a good enough job managing things up front.
There are exceptions, newer dealers may find it easier to get a little bit of sponsorship money for a show or a customer-focused lunch-n-learn because the manufacturer wants to help get things off the ground. Integrators that had a banner year might get a bit of a kickback as an appreciation. If you're historically done a lot of business with me, and I (as the account manager) sense that you might be shifting your interest to a rival then I might also be able to make a case to give you some extra support to keep you loyal.
Personally, I like the new way better. There is no such thing as a free lunch.
If you really want to get sponsorship help from a manufacturer you should be prepared to push hard. Analyze your sales over the last year, look at the number of special discounts you received (if any). Look at the number of deals you originated or closed without needing a visit from the local RSM, SE, etc. If you're generating a good amount of revenue, not asking for a "1 time" discount with every deal, and not taking up the RSM's time on every order you're in a better place to ask for some co-marketing dollars.