In this case, Mr Lemire previously design with collaborators a fast JSON parser (GB/s) that required such bit detection. You can find previous papers in his blog.

Video playback has been moved to dedicated hardware, but it and other kinds of decompression would help. I actually didn't know ARM didn't have popcount.

It's used everywhere in analytics applications and particularly noticeable at scale. For specific example- We use roaring bitmaps (also from Lemire) in an inverted index to make count queries instant (depending on the query and encoding, top-n queries do 20B events per second per core in our application).