Umm… Purina makes Beneful. Royal Canin and Pedigree are made by Mars. Few brands are innocent of making “junk” dog food. It absolutely matters.
To the OP:
Do some research on food mediated DCM. Learn the ingredients to watch for. Then armed with the education, find a food you’re comfortable feeding and your dog does well on. Stay within your budget. Pro Plan is not the only great food on the market.
While I don't think Beneful or pedigree are top tier foods, saying "oh these companies make those foods" doesn't excuse the companies who don't bother to hire board certified veterinary nutritionists to formulate their foods, and refuse to meet the guidelines the world small animal veterinary association has set forth. Those guidelines are not anything extravagant, they are actually common sense and safety minded, yet the boutique brands won't follow them. Several boutique brands have put out false statements that they do follow them to mislead consumers. That's not trustworthy behavior.
As far as nutritionally mediated DCM and researching ingredients to watch for, you can't really do that because we don't know for sure what exactly caused the issue. People have hypothesized that it's legumes such as peas, or it's potatoes, or just poor formulation by the companies who don't hire board certified veterinary nutritionists to create their foods, or taurine/taurine absorption issues (potentially because of legumes) etc. But we haven't sorted that for sure. I hope very much that someone comes up with a conclusive answer, and soon because what we all want is to just be able to feed our dogs safely.