In the last year and a half, I've switched over from Windows to Mac on my personal computers. I had it in the back of my mind that I was going to be doing this, which combined with unfamiliarity and uncertainty about Mac OS, pushed me towards finding some kind of "cross-platform tagging" that would work across both platforms. Call it a kind of hedge bet in case Mac OS didn't work out.
Now that I'm fully on board with Mac OS, however, I just use the native file tagging and don't bother with the hashtags in the file names.