If McDonald's says they are selling fries, they are likely selling fries. I don't care that you've never seen a waffle fry before and therefore can't accept it is a fry and not a hashbrown. That doesn't mean the company is lying.
I mean, they can say New Coke is the same as old Coke, but it didn't stop the consumers from disagreeing. It's why we have Classic now. They also say that about Vernors and how it tastes nowadays, but I'm a bit too young to be fully able to comment there. Food is terrible for this sort of example because small changes can create big changes in taste. I think we've all been to places where they did changes to food you used to like and it wasn't as good as you wanted any more. They can say it's the same, but it doesn't feel that way when you are eating it.
What we have here with 1D&D is, arguably, even more difficult. The dividing line between what people call a new edition or even half-edition and what one might call "errata" is very thin. Does it start and end with class changes? Does it mean changes to combat mechanics? How about changes to the spell system? There are arguments to all of those that we could quibble and debate over, but the line can be set many places.
You know where the line isn't set? Wherever Wizards sets it. They can say it's not an edition change and that's fine, but that doesn't mean much given that they seem to think they have a vested interest in not calling it that. Just because a company says something is the same doesn't mean we should take that line at face value. And hell, I'm not even the guy who is really interested in that debate.
I'll repeat: my argument is not whether it is or isn't, simply that I'd rather it be a half-edition or some such thing because I'd rather the designers have more freedom than less if they are going to make what is likely the PHB for the next decade. Every time we have this argument, I feel people miss that I really don't care what edition you want to call it, I'd just rather they move forward in a manner that gives them more freedom rather than one that makes them beholden to the bloat of the last 10 years.