Even alone, a gerund itself can be a non-finite clause which could feature in catenative (and other) constructions, as “swimming” does in “I like swimming”. So, when should we analyse them as mere nouns and when as non-finite clauses? For my eyes, they should always be analysed as non-finite clauses which have a range of functions that is somewhat similar to what nouns do.
"I like swimming" is strictly speaking ambiguous; it could be a verb (cf. "I like to swim") or a noun as in "I like occasional swimming".
Yes, gerund-participials can be clauses, sometimes catenative, and sometimes not.
Most students in the early stages of their studies are not taught catenatives, so it's always difficult to advise without contradicting their teachers. I prefer the catenative analysis where it is applicable, but as I said "I like swimming" is ambiguous, and sometimes it is better to teach it as noun to beginners.