I agree that it's not a good idea to defrag an SSD. But I'd like to nitpick your assertion that there is no reason. Even on excellent drives, 4k random reads/writes are not as fast as sequential.
For example, the SSD in my machine, a 120gb Intel 330 series, can do ~88 MB/s of random 4k reads, but 500 MB/s of sequential, a multiple of ~6x.
Now, a Seagate 5 TB drive will do 146 MB/s of sequential reads and ~470 kB/s of random access, a difference of ~310x, so SSDs are punished for poor access patterns significantly less.
But it's probably possible to manufacture a situation where defrag would indeed give significant benefits. Whether it's ever seen in the real world is another story.
For example, the SSD in my machine, a 120gb Intel 330 series, can do ~88 MB/s of random 4k reads, but 500 MB/s of sequential, a multiple of ~6x.
Now, a Seagate 5 TB drive will do 146 MB/s of sequential reads and ~470 kB/s of random access, a difference of ~310x, so SSDs are punished for poor access patterns significantly less.
But it's probably possible to manufacture a situation where defrag would indeed give significant benefits. Whether it's ever seen in the real world is another story.
[1] http://ark.intel.com/products/67287/Intel-SSD-330-Series-120...
[2] http://www.seagate.com/www-content/product-content/desktop-h...