Graph databases may be as good as relational DBs. They may be better for some use cases. Are they significantly better for many (say, the majority) of use cases? No? Well then, it's really not an issue that they're what became entrenched, is it?
(And if your answer was "yes" instead of "no": That takes some evidence to believe. And the way this article was written leads me to think that they don't actually have any such evidence.)
As a user of KV stores and graphdbs myself I would have to use a traditional rdbms. It's been an absolute breath of fresh air being able to express queries in a graph-oriented way. For me the combination has been totally "better", but of course, that's not evidence based! Nor, really, could it be.
Well, it's anecdote. But if a statistically-significant number of people feel that it's "an absolute breath of fresh air", that's totally "better" in a very concrete sense.
The first one described relational DBs as a software engineering fail. That's patently absurd. (If that's failure, what would success look like?)
You addressed the second one, which is slightly less absurd. You were taught relational DBs because they are enormously widely used. And why are they used so widely? Because they work.
What the article should be saying is, "Here's this approach that works better than relational, and here's how and why it works better." Mocking relational DBs, as if they had been a failure, just makes the authors look clueless.