Actually - you have started a new thread/conversation. As I have no idea
about (or inclination to find) the last thread/conversation you are speaking
of - all I can tell you is this:
Yes - you can defragment a RAID0 ( stripe set or striped volume ) array.
Not all configurations seem to handle it well, it seems.
Some people have reported complete loss of data after defragmenting such an
array.
However - that is not the norm and who knows what else may have been wrong
with their configuration.
The benefits of such a defragmentation has been discussed before - however -
I think you gain a benefit "overall" if it is done.