Hoarders, or preppers - It is a matter of perspective.
I tend to think of the people buying things up, just because they are starting to get scarce, as the hoarders. The preppers have already bought what they will need.
I was just getting started when the previous dry period started (late 2012, early 2013). I was lucky to find enough to keep me busy during the shortage, but started stocking up when things became available again. I also picked up a pound here, a pound there (mainly at the local gun shows) so I could test different powders. I now know what I like, what I don't like, and what I can use in a pinch, so that is a good thing. I was looking over my 45acp loading logbook, and I have tested 32 different powders to date.
As I remember, the first reloading item to disappear in 2012/2013 were small pistol primers. Could not find them anywhere for a few months. It seemed that once they started showing up again, then pistol powders were gone, or very hard to find. I don't remember bullets being hard to find, though, but that may be because I didn't notice since I had enough to last a while.
Some people claimed not, but I suspect some of the previous shortage was due to the ammo manufacturers buying as many supplies as they could. I will relate an interesting observation I made during the previous "big scare". One well known ammo re-manufacturer would go for a couple of weeks before they would list any 9mm ammo for sale, and it would evaporate withing an hour or two after being posted online. This cycle went on for several months. Then, when it appeared that the market had reached peak prices, they dumped over 1 million rounds of 9mm in one week. I would be willing to bet that they did not manufacture all of those in that one week, they had made them over the previous weeks and were waiting for the prices to peak. Which is their right to do, but I still found it interesting.