I expect this process is for when the DPF is clogged with soot and there is too much for a regen to clear it. The back flush for trucks is to clear out the ash which is a by-product of the regen (and also caused by an engine burning oil or a high SAPS oil being used). If I ever get to the point I have a DPF with too much ash built up, I'll be removing it and backflushing.
I'm very sceptical of terraw**k, forte power-clean etc and anyone who has removed an inlet manifold, EGR valve, cylinder head etc to clean it will know why. I've never found a chemical yet that can dissolve or loosen it so you need to manually remove the build up and you end up with a big pile of abrasive black powder mixed with hard rocks of carbon. If you dislodge this stuff inside an operating engine it can't be good for it. I have a friend who has a service station with terraw**k and he swears by it and has repeat customers - I just can't get my head around it!