"Stupid beekeepers - are they a cause of bee decline?"
To answer the question literally: Of course. Keeping bees requires a modicum of intelligence and if a beekeeper behaves stupidly, then that beekeeper will likely see a decline.
On the other hand, if the question is actually meant to ask if beekeepers as a group are stupid and is that stupidity leading to a decline in bee populations, we must ask what bee populations are were discussing, and where?
"There are nearly 20,000 known species of bees in seven to nine recognized families, though many are undescribed and the actual number is probably higher. ..." -- Wikipedia.
We hear that there are problems with other species besides the honey bee. While some of these problems may be related to disease and pest problems in managed honeybees, I suspect that the majority are not, and are actually environmental.
Many of these environmental problems are related to overpopulation due to the human population boom caused by the warming of the globe over the past ten thousand or so years, and the consequent advancement of technologies which has only accelerated and accelerated since a critical mass was achieved several centuries ago. Only two centuries ago we were trying to build a locomotive that would reliably exceed ten miles per hour. Almost a half-century ago, man walked on the moon.
Human activity has moved just about everything imaginable everywhere, breaking down the natural barriers to movement of pests and diseases and is constantly also spreading novel chemistries worldwide. Ever wonder what something simple like the reformulation of gasoline or diesel additives could conceivably do worldwide and how quickly without anyone knowing?
So, is it that beekeeping activities are causing more than the expected share of the changes, both in honey bees and the many other species? I would suggest not.
And, for that matter, if there is an implied suggestion that commercial beekeepers the only ones moving bees around? I can assure you that more queens travel around the world in the pockets and luggage of hobby beekeepers than with commercial beekeepers. If you are a bee inspector long enough, you learn some amazing things.
Add to that the bio-terrorism that undoubtedly goes on and the accidental transport of all sorts of bugs and plants on ships, and I have to say that no, beekeepers, stupid or not, are not the principal cause of bee decline, assuming that an actual and permanent decline is actually in progress.