Brian tapes all his razors and I believe he does this for the looks as some don't like any wear to the spine but going from taped to untaped is not that many strokes, I believe Glen did a video of this.
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The short answer is the strop flexes.
In the case of a balsa strop or hard backed leather strop it might be a question if you are
using them to extend your hone kit into the very fine range.
If you inspect a lot of paddle strops (leather on wood) some will have rather thin
wood under the leather to allow it to give a bit.
As thin as tape is it is less of a problem than it might sound. Tape also wears
so is thinner in use than when measured.
Good question...