Yep, not to mention work-intensive as well as environmentally-irresponsible.
That is absolutely true ... which is yet another reason not to feed kibble.
Good point, and yes again, some snakes do climb. However, in America, the only climbing snakes are non-venomous (rat snakes, corn snakes, racers and whipsnakes, etc.). Rattlesnakes do not climb and neither do copperheads or moccasins, and coral snakes are burrowing animals, spending most of their lives underground. There are no arboreal venomous snakes in the US ... however in Africa, South America, etc. that is another story.
So, in the USA, keeping your dogs in an above-ground pen is a 100% effective measure, it does not harm the environment, and (once the pen is built) does not entail a constant re-distribution of chemicals.
Jack