Deleting the entire config.txt file would be worse than deleting some (or most) of its contents.
Technically it does not rebuild the config.txt file. Instead it copies the config.txt file from the original session that you saved and submitted to the database before you reopened it and severely edited its config.txt file. When an asset is "Open for Editing" the original is still stored in the database and you are editing a copy, not the original. So if you do something drastic, such as deleting the config.txt file, or deleting so much of its contents that it becomes unusable, then it will not allow you to submit the asset and replace a perfectly good asset with a bad one - at least it did that in my case. That is the reason for the "Revert to Original" option when you submit your edits to the database.