Are "dessen, was" and "desjenigen, das" inter-substitutable?

Question

The question concerns dessen and was in this excerpt from a translation of Camus's The Stranger (by Georg Goyert and Hans Georg Brenner).

For context, Meursault, the narrator, is at trial for murder.

Ich erinnere mich nur noch, daß während der langen Rede meines Anwalts von der Straße her durch alle Säle und Hallen die Trompete eines Eishändlers zu mir drang. Mich bedrängten Erinnerungen an ein Leben, das schon nicht mehr mir gehörte, in dem ich aber die armseligsten und hartnäckigsten Freuden gefunden hatte: Sommerdüfte, das Viertel, das ich liebte, einen bestimmten Abendhimmel, Marias Lachen und ihre Kleider. Mich überkam die ganze Nutzlosigkeit dessen, was hier geschah, und ich wünschte sehnlichst nur eins: daß man hier Schluß machte und ich wieder in meiner Zelle wäre und schliefe.

QUESTIONS

1. Would it be grammatically OK to change them to desjenigen and das? The result would be:

Mich überkam die ganze Nutzlosigkeit desjenigen, das hier geschah...

2. If yes to 1, how do the two formulations sound different? For instance would desjenigen, das be very awkward here?

3. If no to 1, please explain what I may be getting wrong. For example, the two formulation may be inter-substitutable elsewhere but not here for some reason. (I realize this question is indefinite and vague.)

Answer 1

Desjenigen usually refers to a person, but you may use it in other contexts as well. Dessen can refer to something more abstract, an object, a concept, a process.

In your quote, dessen refers to the currently ongoing events. Since the word itself is rather abstract, the author specified what he was referring to in the next part of the sentence:

dessen, was hier geschah

these [things], that are happening here

While I suppose you could form a semantically correct sentence by substituting here, it would be fairly hard for people to understand, since they expect desjenigen to be associated with a person. Associating it with something else sounds like a rather old style of speaking/writing. It might have survived in a few dialects nowadays, although I know of none.