Of course you should. But the debate here is not about how a programmer should do it. The debate here is that Python3 doesn't do it that way by default and at the very least it takes extra code to do it, and as the article points out in some cases like command line arguments makes it impossible to do it that way.
A well designed computer language encourages good code by making it easy and obvious to write it. By that metric Python3's handling of bytes and strings is not well designed.
By the by I have been bitten by this. As others have mentioned a backup program turns out to be a worst case. I had to redo the string / file name handling twice before I was confident it was correct. I'm an experienced Python programmer both Python2 & 3. The final design wasn't obvious to me, and took substantially more code than I thought it would.