Computer scientists often deal with abstract problems that are hard to comprehend, but an exciting new algorithm matters to anyone who owns books and at least one shelf. The algorithm addresses something called the library sorting problem (more formally, the “list labeling” problem). The challenge is to devise a strategy for organizing books in some kind of sorted order — alphabetically, for instance — that minimizes how long it takes to place a new book on the shelf.
You are correct! And moreover, fragmentation was bad on HDDs because they are good at reading sequential data, so fragmentation limited performance by making reads more random. However, SSDs are the opposite and are more performant on random reads, so fragmentation actually benefits them! (some of the time)