[Yetanfou]

Because apple knows ad-blocking is a much-desired feature, and as such can be used to 'convince' people it is time to ditch their 'older' devices (which, technically speaking, have no problems whatsoever in running ad-blocking software) and buy the latest&greatest.

For those doubting ad-blocking works on 32-bit ARM, have a look at the multitude of Android devices. Nearly all of them use a 32 bit CPU. Many of them run some form of ad-blocking software, ranging from proxy-based systems (a la privoxy) to browser plugins to host-based blocking. Often a combination of these are used, all on those 32 bit CPU's.