Although in purely algorithmic terms this does no harm, does it? It still counts as positive engagement. Though it is weird.

I had one today - someone went to three of my stories within about 3 minutes, and highlighted the first line of each. Nothing else.

Assuming they spent less than 30 seconds doing so, this is annoying as it counts as a bounce. Kind of the online equivalent of knock down ginger. Apparently a real person as well, not a bot.