Hidden files and folders - Why the . character in file / folder name instead of using a flag?

What an interesting and educational thread this is/has been! Thanks to the OP for starting it. Thanks to all those who posted their answers to the OP and more thanks to those who turned it into the discussion it became. I was reminded of some things. I learned some things. I took a little trip down memory lane with some names I haven’t heard in years. I thoroughly enjoyed it!