Creating and looking at memes is an indulgent pastime. When it comes down to it, it doesn't really fulfil any major purpose aside from entertaining us, or annoying us. You could use them as a kind of propaganda if you wanted, but most people just want to get across much less sinister and more stupid messages.
Seeing as we're at the time of year when treating ourselves is at the top of the agenda, it makes sense that it is a time to spend looking at as many memes as possible. They might not all be especially on topic, but at least they promise to distract us from everything else for a couple of fleeting minutes. Whatever you might have been doing previously, it's exactly the right time to interrupt it with a meme break. We can't always be on the go and active, and many of us aren't like that anyway.