Overall I like the idea; but it's a shame they call it a cult.
The aspects that give me pause are firstly that it ignores the sentimental associations of physical goods (the treasured gifts, mementos of great times etc.) - but then you can still treasure the memories without having the items; it's just that it takes courage to let them go (and I'm not very brave

).
Secondly, I would miss walking in to a room and seeing a pile of books I haven't read, the sudden reminder of pleasures to come isn't something I get from my ereader.
But, generally, I probably get more satisfaction out of dumping stuff than accumulating it - I sometimes think I accumulate it for the sheer joy of getting rid of it later.