Overall functionality and advantages:

• The script welds separated vertices and later autosmooths the faces if it's needed
• It is very useful when you have imported the file that was generated in other software and the vertices are somehow separated
• You can use these two actions (welding and autosmoothing) together or separately
• Saves time when you have a lot of objects that need welding and later autosmoothing
• The script can work on entire scene or just the selection