I'm not an expert... but I think the blind hem stitch is suppose to give it a hand/needle turn applique look. Since its ---^---^---^ stitches just take wee 'bites' ever few stitches as opposed to the zig-zaging ^^^^^ look.
Personally - I like the look of invisible applique w/ the blind hem stitch. I use this method quite often. But when I want an applique to have an outlined look - then I use a satin stitch with a contrast/complimentary thread.
Blessings,
Donna Mc