A meme's widespread existence only tells that the meme itself is good at survival and propagation - not that it is in any way useful (or that it isn't (or is) harmful).
What does "useful" mean? Survival and propagation are strong indicators.
GP means useful to the 'host' of the meme, that is, to you or me, while the survival and propagation refer to the meme itself. For example, a particular catchy tune might be very successful (very popular i.e. high survival and propagation) but it isn't necessarily useful (to me).
For more extreme examples, consider Nazism or malaria.
Neither of those are widespread in any population. Quite the opposite, they flare up and then vanish.
Fair enough with Nazism. How about war instead? Malaria seems to persist quite well, and doesn't vanish.
When I say "widespread" I'm thinking of being relatively constant for centuries. The sad thing is that war probably is adaptive on some horrific level. I'd trouble naming a country that hasn't survived a war in its past and which has been around for at least a couple centuries.
War is one of those things that's absolutely a survival advantage if everyone else does it but which is nothing but destructive compared to a hypothetical world where nobody does it. Thus we all get pushed into it, even though it's a massive net negative.
Which is incidentally like a lot of other destructive ideas and traditions.
It's more of a prisoner's dilemma. It's great as long as nobody else starts one.