OK, that what you describe is doable for any document format. I never said it is not! But you cannot save that txt, transfer it to another PC or reader and have your notes/highlight preserved. I spoke about the fact that certain formats do not allow to store aditional information related to annotation within document file.
If it is satisfactory for you to have your annotations accessible only in your reader, then anything is possible. Many people need to share annotations with others, backup them and so on.
Even the transfer of annotation work to another device has sort of solution. It would be possible to transfer say txt file and separate file with information about annotations, etc. to another device and read it in a dedicated SW which is able handle both files and show everything like on say M92. It reminds me trials to convert bicycle into Harley Davidson motorbike. Yes, you can add a motor, better wheels, brakes, ... But will it be ever Harley?
I prefer to ride Harley (pdf), even for the cost of converting txt/doc/rtf/html into this format (.... Despite the fact I prefer to ride a bicycle to ride Harley on street.
).
If you or anyone else prefer something else, why not. Do it your way.
