Why is uploading GPS traces "considered harmful"?

Why does JOSM warn me that uploading my GPS traces to OSM is “considered harmful”?

I found a road that isn’t on OSM, so I turned-on my phone’s tracer and walked the length of the road, recording nodes every 5 seconds. At the end of the road, I saved the trace to a GPX file.

I transferred the GPX file to my computer, opened it in JOSM, right-clicked on it, and left-clicked on the “Convert to data layer” button. I then got a popup that said

Upload of unprocessed GPS data as map
data is considered harmful. If you
want to upload traces, look here:

Unfortunately, the link didn’t have any additional information on why this is harmful.

Why is it harmful for me to add my GPX data to OSM? What am I supposed to do to add a new road?

Note: This post is copied from the corresponding post on help.openstreetmap.org

there are 2 main uses of gpx traces in OpenStreetMap: traces can be uploaded to a database of traces, and this db can be used by anybody e.g. as an image in the background when adding data. This feature is accessible here https://www.openstreetmap.org/traces

The other use is having your personal trace in the background of your editing software and use it as additional (or only) information for mapping. Converting these traces into data and upload it is not recommended because it will hardly be optimized. For example in straight lines there shouldn’t be intermediate points, but in curves there should be many points to make them round. Converted gpx traces typically have too many points, have outliers and are therefore not suitable for upload.

Adding the GPS points directly is not a good idea because of the low accuracy of GPS (excluding specialized hardware of course). Instead, you should use your traces to make sure the imagery is aligned and trace it from that. If the imagery isn’t updated yet, you can drive the road several times and try to approximate the road centerline from that.

Good answers are already posted on Why is uploading GPS traces "considered harmful"? - OSM Help

Not really sure what is the reason for appearance for this question here, with the same clickbaity and misleading title.

This message warns only about doing it with unprocessed path.

I’ve closed this topic as the question was already fully and correctly answered in August 2023 on the help site. It isn’t clear what the OP wants to achieve, but it is clearly a waste of time.

If there’s only 1 gpx trace, & it’s your’s, check it with imagery, convert it to an osm layer and ignore the warning. I pay particular attention to the intersections. Many times there are trees obscuring the road and what you have is better than nothing. JOSM has a simplify way tool which should usually be used.