Because, given there are other ways to "save" a site for reading later (reading lists, bookmarks, simply copying the url and pasting into a note, or your browser history), having a ridiculous number of tabs open only uses up resources unnecessarily.
It's not an "advancement" thing....its simply a way to conserve resources and make the phone more efficient. As I said - many OTHER, very simple ways to save a site for reading later.
All the things you mention take an extra step or 3. I do this also, I open multiple tabs to be able to read them later on, it's much easier to just open a tab for later than to do any of the stuff you mention. It sounds like you are making excuses for Safari, which IMO sucks. But by the same token I LOVE iCab browser and it's only on iOS, it blows away any Android browser by far, unfortunately the dev doesn't have any plans to make it for Android.
As for conserving resources, if I can run more than 8 tabs without slowing down my phone then why do I need to conserve anything? Well, maybe iOS does, I'm certainly no stranger to how awful it is for using multiple tabs and graphics heavy webpages.
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\ Next you will tell me I could just use pen and paper, like I often had to do when the iPhone lacked copy and paste.
It's a defiency plain and simple.
Michael
Lol, you mean you don't want to "conserve resources" by using a pen and paper?!?!?