True, I was thinking about that too.
But one aspect of brutalist architecture is "showing how it's made", making infrastructure visible, making structural apparatus visible. And making raw materials visible for what they are, not trying to make them look like something they're not. That's part of it's "rawness" too, as I've always understood it -- it's not just about using concrete.
That part does seem to some extent apply to what's being called here "neobrutalism" in the web. Stark obvious borders and shadows, instead of subtle gradients that blend in and don't draw your attention to them, or which give you photographic or realistic effects to imitate something they're not. Emphasizing the "computer-y-ness" of what you're looking at. Skeuomorphic tries to look like something other than it is; minimalist design hopes you don't think about what the thing is made of at all to distract you from the information -- but this design we're talking about instead intentionally reminds you that you are looking at a computer screen. That's an honest similarity to brutalism maybe.
So, as an appreciator of architectural brutalism, from the headline (and not knowing much about the web design 'trend') I came prepared to make your point... by the end I was begrudgingly saying, meh, okay, fine, close enough. It does draw your attention to the "way it's made" similar to what I understand as actually one of the core values of architectural brutalism; as well as being kind of a challenge to more polite notions of aesthetics in a way that's similar to brutalism's effect even if it's not what the word "brutal(ism)" was actually meant for (although in English at least I think the 'misunderstanding' may not have been wholly unknown/unintentional originally). I guess it's close enough, I'll allow it, I don't need to pick this fight. (although I too wish the author had talked a bit more accurately about architectural brutalism). (On the other hand this design stuff also has lots of non-functional even playful decorative elements, which is contrary to architectural brutalism).