I think the article should come with a litany of qualifiers. What if you're on immunosuppressants? What if your health is compromised in some other form or fashion?
I don't "need" to wear a seatbelt when I drive, I only "need" one in case of an accident. The rest of the time I wear one for insurance.
Same thing goes for filtering water. With most filters rated for thousands upon thousands of gallons one unit is, essentially, a "lifetime use" item if properly cared for. If it keeps me from getting sick just once, it's well worth it. If it keeps that one illness from ruining a trip, then it's worth even more.