There really is no great mystery question - because "machine" is a word not defined by the universe and is controlled by humans, who can use whatever definition they want. So whatever definition you use, this word has no external objective constraints, there will be a common ground between people or not and there is no objective way to make everybody agree on one definition, it's all voluntary. (Even if they do, the agreement is never complete because it's only about the aspects talked about, and then words are not reality and come about indirectly through many processes in the brain and never completely match between different people, or even the same person over time)

"What is a machine" is a great way to waste time doing nothing, unless you can beforehand agree on constraints, e.g. by looking for a definition for one clearly defined purpose. But that's just moving the goal post to a little outside the box that then this definition is tied to.

There is this strange movement, or maybe it isn't strange, when I was younger I followed it too, to take words way too seriously. There's entire fantasy stories about "true names", some kind of absolute comprehension about something expressed as a word. There also are practical examples, for example I once read about a father whose daughter had some rare disease about which nothing really was known. The only thing that had happened, at least by the time of the story, was that somebody had encountered this disease previously and attached a word to it. But without any content, there was no knowledge about how it occurred or how to treat it. But when the father was told that name he said something like "Finally we know what the problem is, I can breath much easier" (words partially made up because I don't remember, but that meaning was there).

Just look at unrestraint, non-concrete discussions about words and there arbitrary definitions, looking for something "philosophical" behind those words. In this context, a blog post I once bookmarked (hey, I finally get to use my bookmarks!): https://www.lesswrong.com/posts/7X2j8HAkWdmMoS8PE/disputing-... - with some practical advice, not an attempt to solve anything "philosophically".

I see sooo many comments here basing their agreement or disagreement on some definition of the word "machine". The default these days is to try to find something wrong with somebody's statement(s), by exploring the edges or even beyond of definitions of some word or words, making discussions very tiring. When instead one could just try to find the idea the person wanted to express and not get hung up about some words. Because deep inside the brain there are no words, the ideas one tries to express are much more fuzzier and flexible and trying to turn them into words is a very inexact process. Our brains don't think in words, except for a tiny part under our direct attention.

The concepts leading to the use of this or that word, and the many words accompanying it, are never the same in different brains, and not the same in the same brain over time. To make the best use of our very limited communication tools that serialized extremely intricate four-dimensional patterns (brain structure plus the dynamic behavior) into rigid words you have to want to communicate and to understand and be positive, at least when something is a little off-center from the usual things that everybody involved in the communication has already established a good synchronization on.

When discussing if we need to buy more milk because there is none in the fridge we have a much easier time with the communication and with agreements, because we are not going anywhere near the edges of well-used concepts (what is milk, what is a fridge, what does "empty" mean, etc. etc. - all of those can lead to deep disagreements at the edges). For a text like the one here some more allowances would be better to get something useful out of the communication.

IMHO the best way to make something out of this article is if you already have a pretty good and somewhat deep comprehension of organic chemistry at least. The many stages of going deeper and deeper down the rabbit hole from the beginning teachings of atoms and chemical bonds to more and more complex understanding that you get from university chemistry, where it gets more like physics, coupled with seeing it "in use" for large and complex organic molecules, is I think a good preparation to understand the article's point.