You can respond more than 1 day later and it’s still relevant!
On Reddit it seems on most major subs if you’re not one of the first to respond, or within 2 hours, then you may as well shout into the abyss.
So much content is being created on Reddit that only the tide of instant opinion (and gratification) sweeps certain posts to the front page before ebbing into history, until someone reposts for karma. I suppose that’s the most efficient and easiest way of filtering posts but there surely must be a better way that does not involve mod (human) judgement. Some forums - like whirlpool or skyscrapercity - have matured enough to be self-regulating and largely appear not to have those problems.