It's definitely not FUD, but it's probably a bug. I'm surprised at how many people are in complete denial that this could be happening and are assuming that people aren't understanding the tooling or something, instead of the obvious explanation, that it's actually an issue.
I was just looking at Disk tab of Activity Monitor, and the numbers just don't make any sense, unless Mac apps are all throwing gobs of bits at the disk for no particular reason.
For example, in two days of uptime it says the SafariBookmarksSyncAgent has written 1.94 GB to disk. I haven't added any bookmarks to my machine in those two days and I haven't used Reading List, so how is that even possible?
As other's have stated, it's possible that SafariBookmarksSyncAgent has a process that regularly writes to memory (object creation and garbage collection) and that memory is being paged to disk.
