No, no one said it 'ruins' the experience - only that it doesn't belong and detracts. Then there was some people that argued once outside the parks.. no one cares.. which was another part of the discussion.
I also addressed before that there is a nature of 'practicality' when it comes to bringing in elements that you may not otherwise see as fitting into the vision for the project/space/experience. You can not live in a world where you hold a position those undesirable things to NOT exist and that you can exclude EVERYTHING.. and no one is holding Disney to that standard. It's about what you DO with those things and how you integrate them into the experience, or do it in a way that minimizes the negatives.
Sponsorships is an example of those practicalities - no one is holding a standard that says they should not exist, and no corporate presence should be there. But its about HOW it's done. Disney's success with avoiding 'over the top' with this of course has blemishes in its past (people's take on UoE's message for instance)... but it's not uncontrolled or glaring. You wouldn't find a FedEx truck parked in front of Space Mountain. People point to them existing from the start.. Yes, because Disney needed the money. And as soon as he had the money, he took control again and bought them out. Sponsorships were a means to an end for Disney... not simply "well they exist everywhere else, why not accept them here too?" justifications.
The earlier examples I gave about safety are another example where Disney has worked to make these practicalities either minimize, blend, or disappear from the consciousnesses. The stories about how Disney has hidden fire safety systems in the parks are another great example of it's not an expectation that you EXCLUDE practicalities... its how you work with and around them to ensure they cause the least amount of disruption to the guest experience.
The very nature that parks aren't a hop skip and a jump away are another one of these practical aspects that Disney had to address. To do it in a Disney fashion, they built out their own transportation service that could operate to their standards of both customer service and show. Transportation is a practicality... but none of that says moving billboards are just part of transportation that can't be avoided or has a place in this experience.