Are there like any use-cases for it other than "well, I can add another drive to extend partitions whenever I want"? 'Cuz that's how it's often described (if at all*), and it doesn't really make much sense to me. Like, if I install on a laptop, it'll most often have just one drive, so lvm seems unnecessary, and if I make some server-like setup with multiple drives, I'd go with some kind of raid with redundancy instead of just stitching the drives together (or mb yolo and raid 0).
* If I remember correctly, arch wiki for example, had it used in the partitioning guide for dm-crypt without explaining the benefits against just luksformat
ing /
Well, there's PWAsForFirefox