Reposting might be an unnecessary but important feature of social networks in general, in order to drive continual engagement.
The difference in engagement will often be driven by in the quality (or lack thereof) of the comments section. Salient familiar declarations may well prove to encourage replies that reference memetic icons of the latent culture; though poorly placed ones may leave a comment section bereft of replies.
Genuine original content is rare but may also be wasted for the location in which it has been planted. Attempts to break the fourth wall may be met with ambivalent results.
But reposting will always remain valid; even (and especially) when it may feel like a humorous and fashionable way to scream into the void.