While I do believe that in some cases they are appropiate, funny, wholesome memes, more often than not, they are inapropiate and often put down people's cultures, relgions, and identites. They can be really offensive and hurt people. An example of this is the whole sombero thing with people from Mexico. They are countless memes that say that all Mexicans wear somberos, speak Spanish, and eat Taco Bell. Memes like this stereotype cultures and stereotypes hurt people more than most think. Most people don't realize how much words can hurt. Memes are just making fun of people and their cultures and while some are entertaining, is it really funny to laugh at someone's lifestyle? Their heritage? Their culture? Their life? I don't think it is.
I think you have confused stereotypes with memes because there is no correlation between the two. Memes may not be the most appropriate or popular form of entertainment but they are a form of entertainment nonetheless. Memes do not mock or tease the lifestyle, heritage, culture or lives of others, rather they provide a form of unity for people to come together for a good laugh. Some memes are inappropriate but still provide some comedic value. One's view of memes should be looked at full scale rather than with a magnified glass. Memes overall effect on society is positive and good.