There is a reason to do
and not otherwise. If 'blah blah' happens to be a block of code you commented out, you want a fast method to uncomment: just remove 2 lines.
For a single line commented out, // at the beginning might be better for that use.
But certainly those are comments while you are still debugging your code, and not something you want in a 'production' release.
Then in 'release' code, it boils down to readability and personal taste.
... and I do personally like nice "boxes"!