enzymes only deal with naturally occuring stains .. blood, sweat, egg, grass etc
so if you are not prone to getting these type of stains in / on your clothes then bio isnt necessary ... as for allergies / reactions the perfume in detergent is more of a reactionary than any quantity of enzymes .. this is one of the reasons that manufacturers are now producing alternative fragranced detergents .. so that if you have a reaction to one you can use / try another and hopefully not suffer any reaction .. thus they keep you as a customer !
As for the bacteria that remain in your machine due to our love of ever reducing the temperature of our washes .. these are left behind more and more owing to our love affair with liquid detergents and their lack of bleach ( NO liquid or capsule detergent contains bleach ) .. low temp washes combined with no bleach in a majority of washes ( if not 100% ) equals bacteria left behind which accumulates and over time breeds & starts to smell ..
happy wash day !