No he says in the first sentence I quote that 4e has this problem right down to its core.
And I'm pointing out that if it does, then earlier editions did too.
So, starting off, there's a LOT of evidence for bad 4e naming conventions. Darkfire doesn't stand alone. It is not the sole piece of evidence. 4e has this problem in many areas. Darkfire is one (not even particularly bad) datapoint, but there are so, so many more.
But hey, earlier editions don't get a pass. There's some evidence for cruddy names from earlier editions. The difference between them is more about those have a bigger problem with being "too exotic" (ixixachitl, aasimar) than "amazingly dumb" (Feywild, Wilden, Shadowdark).

I'd also argue that they weren't nearly so prevalent or central to the game (monster names vs. place names and power names). The case for 4e having bad naming conventions goes far, far, far, far, far beyond this one power. If you'd like to make a case that older editions were no better, okay, but you'll have to provide more than this as evidence, you'll have to overcome the "exotic vs. dumb" comparison, you'll have to show centrality, etc. That's a whole separate conversation, and it doesn't absolve 4e of being ALSO bad, though it might show that D&D has a long history of horrible, horrible fantasy names. At best, we're all wallowing in the same mire. Not sure I'd buy that, but you'll need more than "This power was also confusing back then!" to convince me.
So, this fire-based confusion doesn't mean that 4e doesn't have horrible naming conventions, and it also doesn't mean that earlier editions did, too.
But let's look at Faerie Fire. With that name, there is a
Mythological Basis Trump Card that is pretty evocative, and puts an image in the mind of someone vaguely familiar with myths or fantasy literature that use the myths. Which is what D&D does well. There may still have been some confusion, 'cuz not everyone's up on their Welsh mythology or whatever, but in grand Gygaxian fashion, D&D with faerie fire is edutainment.
Still, even with that trump card, it's probably not the best name. Your/my criticism remains valid. Evocative and mythological, but still confusing for the newbies. It's fire, but not fire, and this is probably not the first time in that power's history where someone thought it would melt ice. When they revisited the name in 4e, they clearly agreed that it could use a change, because they did change it. But they didn't think the "fire" part was problematic at all, just the "faerie" part. Which they changed to "dark." Because clearly the word "dark" doesn't get used enough in a D&D game? While "faerie" suffers from over-use? And they didn't know about potential "fire" confusion? Despite "fire" being almost as common as "Dark"?
I dunno. I don't know what they were thinking. But I can say that Faerie Fire -> Darkfire is not an improvement in any way in my eyes, since it retains possible confusion while obliterating mythological resonance, making up a newcompoundword and risking over-use singularity of the term "Dark."
So, take an evocative but probably confusing term, and turn it into a bland and probably confusing turn. Which is further evidence of 4e's bad use of names.
Though I will say that problem seems to be getting better. The only groaners I found in the Underdark book were legacy imports like "Shadowdark," "Feydark," "Swordwing," etc. Didn't see any "Darkcrawlers" or "Deepdwarves" or "Swordcrawlers" or anything.