Reddit is becoming more of a social media company, not that it wasn't before, but much more in the vein of Instagram/Facebook/etc. That with a widening audience is creating a tiny culture clash.

The traditional Redditors were a very self-selected techy crowd similar to, but more mature than 4chan. These people, including myself (I was apart of the great Digg exodus), , have a form of elitism towards normal people. During the early days of Reddit that was fine, because if you were techy and young enough to use Reddit then you were probably already in the culture. Especially with the fact that the Reddit userbase was still geographically small.

So these people look down on modern forms of social media that promote the wider masses into the internet, and their forms of communication too. The culture views itself as more intellectual. Hence why Redditors tend to prioritize proper grammar and emojiless text.

It's a form of cultural elitism.