We have BINGO.
It doesn't have to be about the national/international corporation being the sponsor, the local distributor is all you really need to start with. I would bet a fair amount of money that those in this thread that point out that big companies "used to" sponsor disc golf are probably confusing what were actually sponsorships from local distributors and/or franchises for sponsorships from the larger corporation.
Just as an example, if you look at a lot of the USDGC's promotional stuff (posters, programs), there is a Coca-Cola logo amongst the sponsors. From that, you might infer that is THE Coca-Cola corporation that sponsors the Olympics and advertises all over TV. But in reality, it's simply the local Coca-Cola distributor in Rock Hill. Still Coke, but not the one that could potentially funnel thousands if not millions of dollars of support into the sport were they so inclined. But maybe if relationships are maintained and nurtured, bigger things can grow out of these little ones.
That's the really frustrating thing about threads like this that start with a suggestion of what "they" (PDGA, regional/local club, TDs) should be doing to get brand X involved in the sport. It all starts with you. Go to a local distributor (hell, write a letter to corporate if you want). What's the worst that happens, that they say no thank you? If enough local distributors or franchises of larger corporations are giving some support, maybe corporate HQ starts to take more notice. But it isn't going to happen overnight and it's never going to happen if people are content to sit on their hands and wait for "someone else" to do something.