Jirachi was a good scarfer in HGSS, because it could renvenge some of the best sweepers in the metagame (Gyarados, Mence etc.) the only common thing it can revenge now is Terrakion so people use sets like SubCM and SDef Jirachi because they are much more effective in the current metagame.
It also still gets U-Turn and Fire Punch so Ferrothorn shouldn't be that much of a problem.
The biggest problem of scarfers are the dangerous set-up threats this gen. Things like Terrakion, Volcarona, DNite, Landlos and the rising Lucario and Salamence got lots of resistances/immunities they can use to set-up on and start a sweep, however Team Preview can help with that.