Plain text is compact, but if talking about purely text documents there isn’t much practical difference with other formats. They will be larger but there are indeed multi-GB storages nowadays.

Oh yeah, HTML is a mess – especially if copied from Internet Explorer.

Good point. Even techies tend to forget just how much of meta information gets stuffed in file with complex formats. And regular users are oblivious altogether.

But even for plain text privacy is often undermined when it is printed. Laser printers are known to add secret marks to printouts.

I think in following years privacy will either erode completely or it will go the way of explosive cryptography and darknets growth. With former more likely. :)

Plain text does not contain hidden information. No user data, no information about your PC, OS or folders, no deleted text. With plain text, you do not store information or pass it on to others unintentionally.