Unlike hard drives of yore where ordering the drive to write a bit at a given location results in the drive writing a bit at a given location, SSDs abstract it

Unlike hard drives of yore where ordering the drive to write a bit at a given location results in the drive writing a bit at a given location, SSDs abstract it away as a matter of their design. An SSD will still provide a virtual bitmap so file systems can still order it to write a bit at a given location like ye olde days, but the SSD controller ultimately decides where to actually write that bit which more than likely has no relation to the specified location. Incidentally, yes: This also means defragmenting an SSD is not only harmful, it is outright misleading because the state of the file system is not related to the state of the bits on the drive.