Recently I looked up an explanation for 文節【ぶんせつ】 on here 国語文法, which I learned are the phrases/units that make up sentences while theoretically still standing on their own out of context.

During that explanation they used the concept of ネ・サ・ヨ to illustrate their points, by separating each 文節 of a sentence with one of these. E.g.

「机のネ/上にネ/バッグをネ/置いてネ/おく。」

I didn't understand why at first as this seemed rather specific for an arbitrary separator, so I searched for other mentions of ネ・サ・ヨ on the net. What I found was only a mention of some movement around 1958 in some elementary schools to avoid using these sounds at the end of sentences, as they were supposedly not part of standard language. See here.

From that I pieced together that in the initial 文節 explanation ネ・サ・ヨ were used because conceptionally they could be appended at the end of each basic phrase in a sentence so Japanese people might have a natural feel for what a phrase/文節 is.

That's all just my limited speculation however, thus my question:
Is ネ・サ・ヨ used with any frequency in Japanese grammar explanations, and if yes, to what end?