7za (the compression app) does blazingly fast iteration over any kind of folder. This doesn't require special code for git. Backblaze's backup app could do the same but rather than fix their code they excluded .git folders.

When I backup my computer the .git folders are among the most important things on there. Most of my personal projects aren't pushed to github or anywhere else.

Fortunately I don't use Backblaze. I guess the moral is don't use a backup solution where the vendor has an incentive to exclude things.