&quot;... people who cannot edit &#x2F;etc&#x2F;hosts, but can change DNS server.&quot;<p>e.g., &quot;mobile&quot; or &quot;tablet&quot; users who choose Apple iPhone, iPad, etc.<p>The idea of an ARPA-networked devices that have no user-editable HOSTS file seems inferior to ones that do, i.e. the vast majority of ARPA-networked computers for three decades, but that&#x27;s just my uninformed view.<p>The experts selling these things must know better.<p>DNS works very well for blocking ads.  It allows for things that cannot be done with HOSTS alone.<p>But if you trust a third party for your DNS resolution needs (ad-supported search engine company &quot;free&quot; public DNS, ad-supported, corporate-sponsored browser, etc.), then all bets are off.<p>If and when advertisers complain and start to cut back on spending, then these third parties could remedy the situation, easily.  In my opinion.<p>If the user is running her own DNS services, then it may be too much trouble for advertisers and the companies they prop up.  It is a stretch to think that any ad-supported company could stop users from exchanging lists of names and numbers, whether through a HOSTS file, zone files, or some other mechanism.