I have always wondered where the assumption developed that the primary use of biscuits is for alignment. I don't know how many times I've read the comment that "biscuits are for alignment but add no strength".

Lamello invented biscuit joinery. If you go to their website and look at any of the demonstration videos, you will see them demonstrate lots of corner joint applications, T joints, face frame attachment, reinforced miters.
What you will never see them demonstrate is biscuits in a long grain edge glue up.
Not that you can't use them this way, but it's just not an application where they are particularly special.

Sometimes it's easier to take the tool to the work, especially if the workpiece is large. Here's a good way to use a biscuit joiner to insert a spline in a mitered picture frame:

biscuitspline.jpg