If the average meme has but one purpose in its fragmented and often short life, it's to get the message it provides spread out in the world as far as possible (unless it is genuinely something very niche). They want to ascend quickly, spend their limited time in the spotlight, and then fizzle out to possibly be repeated on the less relevant fringes of the internet for years to come. It is a time-honored process that the average meme consumer has no choice but to respect, as it's just how things tend to go in the ecosystem. If you want to be philosophical about it, it makes each new funny image that we stumble upon a special event as for all we know, it might not last that long. We may not remember every meme that we look at in our life, but we will likely share many that amuse us.