Probably because ctrl-R doesn't present you a list in most shells. Maybe you want to scan the list visually and look at neighboring commands. ctrl-R doesn't really take advantage of human vision by showing all results next to each other.
That's pretty much it. I used to have to use quite a few different shells, so `<CTRL> + r` wasn't always available, but `history | grep` usually was. Once I'd got in the the habit of using `history | grep` I found that I liked the extra context provided by seeing a group of commands with a few variations between the lines. So often it helps jog my memory of what parameters I'll need to change before using it.
For me that’s it indeed; grep, sometimes with -A -B is much faster in general for me because it might be similar commands which now will appear next to eachother.
