One guy on YouTube from Canada that generally does target related stuff said that 6.5 CM generally are more accurate than other calibers that he tested in the exact model rifles. I think that's a significant reason.
The BC for 6.5 has a lot to like for windrift and drop at longer distances. At closer ranges, I think it compares favorably with 7mm-08/243/308. There are a lot of loads available and rifles of almost every type. It's a very efficient cartridge.
Fwiw, I don't have one. But, I've thought about it.