when die acts as a relative pronoun, it's just a usual construction not dissimilar from
Ich mag Erdbeeren, die süß sind.
you might find "diejenigen Erdbeeren, die süß sind" or "die Erdbeeren, die süß sind", too. All those are questionable constructions, but nothing unusual. Using diejenigen like that is as useless as an unspecific "es" (I hope you know what I mean). That is to say, it does serve its purpose, but it's rather colloquial. I'd consider it unlucky, not to say wrong, if a definite article, and derjenige, diejenige in this sense as well, should make a back-reference to a known entity--e.g. "Wir haben Erdbeeren gepflückt. Die Erdbeeren waren süß".
It is not all too different from a bare diejenigen die, as far as I understand. Compare:
"Und dadrauf satteln diejenigen, die ...".
I wouldn't give one a preference over the other. English in comparison knows a strict proscription against dangling prepositions, though, as you might now, that is frequently disobeyed.
diejenigen would normally refer back, as I said, to a limited subselection: "Da sind vier Personen. Drei von denen tragen Hut. Ob diejenigen Haare haben, weiß ich nicht, doch die vierte Person hat eine Glatze." In a construction like this, diejenigen is actually necessary to disambiguate.
I think it's likely that the set phrase diejenigen, die developed to avoid a (phonetically unpleasent?) reduplication as in "Ich mag die, die süß sind."
jenige normally refers back to an already introduced entity, as I said: "Ich mag Erdbeeren. Vorallem diejenigen, die Süß sind." This can be transposed to the above example. This becomes obvious comparing
"Ich mag (die) Erdbeeren. Vorallem die süßen."
"Ich mag vorallem die süßen Erdbeeren"
"Ich mag Erdbeeren. Die sind süß"
"Ich mag (nur) die Erdbeeren, die süß sind".