Agreed - and while most of this is obvious, and some insightful, some of it is just baseless opinion:
"Never underestimate how much havoc you can create by indenting with tabs instead of spaces..."
Conversely, never underestimate how much havoc you can create by using spaces for indentation. With tabs, the level of indentation is clear and atomic. With spaces, it is arbitrary, and, wait for it...
As someone who, despite being 24 years old, learned to type on a (mechanical!) typewriter, I don't like tab for indentation on the basis that, for me, tabs have a very specific meaning:
Carriage (or cursor, if you prefer), go to the next tab stop. [2]
For typewriters it means to go "literally" to where the next stop is. For text editors (at least for emacs)[1], it means to insert as many spaces as needed so the next column on the current line matches with the last non-space column on the previous line.
So, in the same way I use the table tag for tabular data in markup, I use the tab key for tabular text.
Conversely, never underestimate how much havoc you can create by using spaces for indentation. With tabs, the level of indentation is clear and atomic. With spaces, it is arbitrary, and, wait for it...
hard to maintain