Is there a meaningful technical difference between an language and a dialect (of some language)?

John McWhorter says, "no", in an article in The Atlantic. Here's how he opens:

What’s the difference between a language and a dialect? Is there some kind of technical distinction, the way there is between a quasar and a pulsar, or between a rabbit and a hare? Faced with the question, linguists like to repeat the grand old observation of the linguist and Yiddishist Max Weinreich, that “a language is a dialect with an army and a navy.”

But surely the difference is deeper than a snappy aphorism suggests. The very fact that “language” and “dialect” persist as separate concepts implies that linguists can make tidy distinctions for speech varieties worldwide. But in fact, there is no objective difference between the two: Any attempt you make to impose that kind of order on reality falls apart in the face of real evidence.

From his final two paragraphs:

Or, yes, the written dialect will have its words collected in dictionaries. The Oxford English Dictionary does have more words than Archi and Endegen do; the existence of print has allowed English-speakers to curate many of their words instead of letting them come and go with time. But words are only part of what makes human speech: You have to know how to put them together, and knowing how to handle Archi’s words (or Endegen’s) requires its own level of sophistication.

So, what’s the difference between a language and a dialect? In popular usage, a language is written in addition to being spoken, while a dialect is just spoken. But in the scientific sense, the world is buzzing with a cacophony of qualitatively equal “dialects,” often shading into one another like colors (and often mixing, too), all demonstrating how magnificently complicated human speech can be. If either the terms “language” or “dialect” have any objective use, the best anyone can do is to say that there is no such thing as a “language”: Dialects are all there is.

I've not read the whole article (I skipped to the end), but I'm biased in McWhorter's direction. In fact, I believe that all that exists (physically) are individual idiolects. But constant communication among individuals assures that these idiolects are mutually intelligible to a considerable extent, yielding dialects.