I use a Garmin Legend - and found that saved paths wouldn’t upload to OSM. I then found a page by Farzaneh explaining the problem with a python script to fix it.
I don’t use python, and only run on windows, so wrote a similar utility in javascript to run on the windows desktop (using standard ‘open file’ dialogs etc) - so a single click is all that is required and you can have short cuts etc.
I have been thinking that the timestamp thing is there to make it harder to just convert some GIS data from shapefiles or some other GIS format to GPX and upload them. Timestamps added by some utility are easy to recognize from the modified GPX file because driving speeds do not make sense. But I don’t know if this is the real reason. Perhaps because of another secret rule JOSM does not convert GPX waypoints to OSM points even it shows them.
I have dug around a bit more and I think time is required to help ensure that you were ‘really there’ at a particular time - the point wasn’t inserted by some software and so might be copyright in some way.
i.e. When you clear paths on a Garmin, it automatically adds some points representing its various offices to the start of you active path log.
If so then my script disables what is basically a ‘security’ measure, so is not a good thing. I am happy to remove it or add a health warning if asked.
Or the XSL could be modified to filter out known copyright data… Or maybe remove points that are more than (say) a mile from the next?