Well, you don't get as many collective up votes. If you have say, 4-5 really good memes out there in the most popular streams you will gather many more up votes as well as comments. When you have a large quantity of memes people are not as likely to engage as much, or scroll your page to up vote them all. It starts to feel like work basically. You notice I don't have a ton of memes out there. I am very active in comments though. I am not hurting for points at this time. Basically, it is better to get a great meme that makes it to the front page than to have 10-15 get just a few up votes each.