I've often seen this happen. A few years back I applied for a job at a startup where I checked a lot of the boxes, but not all, but some of the boxes I checked were difficult to come by - never heard anything back. Six months passed and I was contacted by them, would I be interested in interviewing? I was and I ended up getting the job. Later when I asked about the position being open for so long I was told by one of the people involved that there were folks who were waiting for the perfect candidate to come along and finally, after many months, they were convinced that the perfect candidate probably didn't exist. So yeah, there's at least one instance of it where I know for sure that's what was going on and I've seen others where I'll watch a job listing keep appearing for several months.