I read the book, "harsh" seems like the exact opposite of how she writes, but she does advocate strongly for her technique. Really there's not much to the whole thing. You pick a category of your stuff, gather everything you have in that category in one place, evaluate what you have, pick out only the stuff that you really love (and not stuff that you keep for guilt or worry you might need it or whatever) and move on. She has an order to it, start with clothes, various categories, and then do sentimental stuff last.
But I do mini versions of the technique all the time. I gathered all my spices one day, discarded really old musty stuff, tossed some I never use but bought once for a recipe, combined duplicates, and reorganized. I think the big pile helps you understand that you have too much or duplicates or stuff you never use. Doing a drawer ay a time (as I've seen in other declutter blogs) leaves you with, for example only, too many pens spread across many drawers. You never do get on top of what you have in total. I have this struggle with my husband where he buys the same household cleaners over and over because they are split up between under the kitchen sink, in the laundry room, and in the main bathroom. He doesn't look in all the places. So, my next project is gathering everything in one place.
The goal isn't to achieve a minimalist home, it's meant to leave you with things that make you happy and enhance your life.