I'm new to Sprinters and more specifically new to diesels, so this biodiesel labeling/use issue is really disturbing to read about.
Keep in mind that you may be reading posts by people who have no idea what they're talking about. The best idea is to try to stick to the facts. The tricky part is nailing down facts. I'd do things like read your owner's manual to see what Mercedes says about bio diesel in your specific vehicle. I would not be surprised that the owner's manual has changed between 2007 and 2017.
After reading all this, I have to ask, am I to assume that I will often be driving where it will be difficult to find 0-5% biodiesel fuel and when I think I've found it I won't know for sure because the labeling may not follow the federal guidelines and/or what is shown in the MB biodiesel brochure? Any states besides Illinois where this is more likely to be a problem?
There are a couple of farm belt states that apparently have mandated a minimum percentage of bio in all diesel. There was another thread recently commenting on a different state (WI? MN? SD? I want to say it was in the upper Mid West and not IL.) that had mandated B20. Lots of people were in a panic. Calmer voices did a bit of research and discovered that the requirement was being phased in over the course of a few years. Currently, the minimum was B10, and not B20.
My understanding is that it is a federal law or regulation that requires pumps dispensing biodiesel greater than B5 be appropriately labeled. I have no idea who enforces this, nor do I know how widespread any disregard of this particular Federal requirement might be. I do think it's reasonable to consider that pumps which should be labeled might not be. I also suspect that disregard of the law is more likely at off-brand independent stations than it would be at nationally recognized brands.
All this makes me wonder if buying a diesel was a hassle-filled mistake!
Being a German company, Mercedes may not be closely in touch with some of the state and local politics of fuel in the US. And they may have made the decision not to worry about those politics very much. Diesel vehicles are a much smaller portion of the market in the US than they are in many other places around the world - particularly Europe, where small diesels have been popular for many years. It could be a business decision that catering to localities legislating higher bio percentages in diesel fuel is something that is not worth their time.
It's also possible that Mercedes is simply being very conservative in their fuel recommendations. In short, dino-diesel is almost always going to be a more consistent, higher quality fuel. So they specify that fuel. Biodiesel can cover everything from large commercial operations which produce a consistently good fuel to home distillers producing who knows what. It may be easier to recommend the known consistent fuel and avoid the confusion and/or complexity of trying to separate one biodiesel from another.
At lot will depend on your particular location, or the places you plan to frequently use your Sprinter. If those frequent locations are all in biodiesel territory, then you need to look into the issues further and make your own decisions. If you travel to those places only on rare occasion, I wouldn't worry about the issue much. I doubt if one or two tanks of B20 (assuming good quality B20 and not some home brewed unknown) are going to cause you any issues. A little research into the areas to which you are traveling can help with planning around biodiesel issues. Filling up before entering an area that requires higher biodiesel concentrations, and topping up early with bio (to keep the actual concentration in your tank down) are ways to deal with brief travel. It's also perfectly fine to simply fill up from recognizable sources and go on your way.
The only time it's a real hassle is if you live in an area that requires higher biodiesel concentrations and don't leave that area often. In that case, choosing a different vehicle might be a good choice.
The Sprinter ads never mention the fact that owners will sometimes have to hunt for a gas station that has the proper fuel 
