As the article points out, the big change is in the production levels and the price. If meth is cheap and every dealer is flooded with it, more people are going

As the article points out, the big change is in the production levels and the price. If meth is cheap and every dealer is flooded with it, more people are going to be using it and in higher quantities that will produce more visible (and negative) effects. The random apartments are probably stash houses used for storage of bulk quantities that would be broken down and distributed to dealers.