Shaver:"Some of the most harmful ingredients in dryer sheets and liquid fabric softener alike include benzyl acetate (linked to pancreatic cancer), benzyl alcohol (an upper respiratory tract irritant), ethanol (linked to central nervous system disorders), limonene (a known carcinogen) and chloroform (a neurotoxin and carcinogen), among others." source Scientific American.
That "fluff" is great for the compost pile! And you can buy long brushes to periodically clean out the vent.The fluff which accumulates in the filter of a dryer previously comprised the fibre of the cloth. One's garments deserve better treatment.
Also, "2,900 home clothes dryer fires are reported each year and cause an estimated 5 deaths, 100 injuries, and $35 million in property loss" according to FEMA website.