I've seen that claim before and I think it is another case of using the same term to explain something different. Microsoft is infamous that. Think of Windows Explorer, File Explorer, Internet Explorer, Outlook, Outlook Express, Outlook.com, Windows Defender the antispyware programs and Windows Defender the antimalware program.
All disks, HD or SSD, have storage locations of fixed sizes. These are called sectors. If a file is too big to fit in one sector, multiple sectors are used. Mapping information is used to tell the drive's controller where to look for the next sector. On a hard drive, it tells the R/W where to move to. On a SSD, it just accesses it directly. But again, on a SSD, it does not matter if that next sector is right next to the first, or not. In fact, after TRIM is run, it may be moved any way.
So instead of calling it a "kind of defragmentation", IMO, they really should say it is something along the lines of "metadata compacting" or something like that because if a file on a SSD takes up 6 sectors, before this process is run, it will still take up 6 sectors after.