It was actually pretty much a DMC2->DMC3* situation, I think. Before the trip, the manga had been getting less interesting for people due to the repetitive nature of it. I know I, at least, had dropped it quite a while before the trip, and was vaguely interested as the arc went on but mostly didn't really care. The scanlation had to have really sealed the deal though.
(*note: DMC2 was such hot garbage that, although 3 was incredible and is often argued to be the best in the series, it had the weakest sales of the whole franchise because nobody was interested after that shitshow; not that Watamote was DMC2 level bad, just not as strong as later parts)