Yeah, sync/rebuilds are all about seeking around through thousands of tiny little tags files. And SSDs take effectively zero time for seeks! Compare that to mechanical drives, where seeking is what they spend almost all of their time doing.
The /proc/partitions thing just shows the Linux kernel's view of what drives and partitions it knows about in the system -- those that actually exist. It doesn't mount them or anything, that's up to the system scripts or the end user.