It might be that it’s hard to find for high-volume posts, but my site has basically no high-volume posts, to a first approximation. It’s generally lower-volume, but often people don’t select and hit “quote” to make it clear to whom they are responding, and then confusion ensues.
While this mega-thread may be a stress test of the experience, it doesn’t say much about how useful this feature as it stands today would be on a site like mine where the conversations are more technical, where it would reduce the reliance on people selecting and quoting context to clarify the responses.