I raw feed my dogs and no longer vaccinate them beyond first booster after puppy vax, but I DO worm mine every 3-4m as they visit fields where livestock go on.. but also worms can be passed on to children as well as causing many problems including lungworm and even heartworm as mentioned above.
Do you really think a tablet per dog every 3m is such a big deal when it prevents so many problems for multiple species?? You can even worm naturally if you are worried about chemicals - things like verm-x make the gut less parasite friendly and DE can be used to dessicate any parasites present, but both are more effective if you start with an "empty" gut as they have limited use against large numbers
Toxocara, Toxoplasmosis, Tape worm ALL can be passed onto people as well as animals (and the tapeworm is linked to spread from fleas too) and you need a massive worm burden in an animal to see signs. You can also pick up worms from rabbit fleas (or fox fleas).
So tapeworms are actually one of the easiest things to catch, even in a "closed" environment... just sayin'
