You do not need to "rescue" alone to help. Fostering is a wonderful option, where guidence, support and training is also given.
I dont like the term mutts personally, the dogs i have rescued and fostered are valued and cherished members of the family. They are no less loved and cherished than other breeds and have just as much to give and offer. They certainly do not pale in insignificance to pure breeds in their families eyes.
It will be a bloody brilliant day when rescue in general are able to simply focus on chosen breeds. Even better when there are a managable number of any breed dogs to help! As things stand, that is impossible and it is rapidly becoming very much worse.