How do we ensure the site stays un-fluffy?

This seems like a tricky one to me, as it largely depends on the community as a whole deciding to go with a particular tone.

One example of a site that has an expectation of serious conversation is Hacker News, and this makes it a great place to get thoughtful discussion without snarky comments (but with its own biases and echochamber effects of course).

What I don't want to see Tildes become is the meme-posting, reference-laden, low quality noise of some subreddits, or the content-free fluff of Imzy.

How can we strike this balance?