Safari crashes when it gets low Ram. It seems to be just a feature of the memory management system, and why some sites crash more than most.
That is likely what crashsafari.com is doing, filling the Ram so tat Safari crashes.
If you use an adblocker, obviously you get more joy from the low memory resource made availlable, at least on regular sites.
IOS is a mobile operating system, and is simply not designed for full blown PC like experience for web sites. Android is similar but is certainly closer to how a normal PC works.
Chrome works on lower Ram by giving a compressed image data saving option.
If that option is on IOS Chrome, you had best tick it.