It’s probably a thing, especially with loan-words (eg.: “avant garde”), and there are probably much better examples… But the examples in the article make no sense to me.

The difference between phrases and "words with spaces" is addressed.

The confusion might be that this seems to be a spectrum rather than a binary phenomon.

We have single words at one extreme, ordinary sentences at the other, and in the middle we have idiomatic assemblies of words that span a range of substitutability.

"Hot dog" and "Saturday night" are arguably great examples, because they exist at the opposite extremes of the spectrum. Saturday night can retain some of the original meaning following substitution, whereas hot dog almost deserves a hyphen.

I think 'phraseme' is closer: https://en.wikipedia.org/wiki/Phraseme

Imagine configuring your word separator like this: " `~!@#$%^&*()-=+[{]}\|;:'",.<>/?"