It should be opt-in per website, per feature, because IMO it can be quite useful in some cases. Like clicking back on a slide-show bringing you to the overview page, instead of only going back one slide
> clicking back on a slide-show bringing you to the overview page
That behavior is expected in exactly one case (assuming slides, not the whole presentation, are modeled as a page each): If I navigated to that specific slide from the overview.
In any other scenario, this behavior amounts to breaking my back button, and I'll probably never visit the site again if I have that choice.
Opt in features are a great way to increase user frustration and confusion. See the whole new geolocation API they had to make for browsers since people would perma-deny it reflexively and then complain that geolocation features weren't working.
That's a good point, though I'm not familiar with the (changes to the) geolocation API you mention. Do you have any recommendations for reading up on that development?
That behavior is expected in exactly one case (assuming slides, not the whole presentation, are modeled as a page each): If I navigated to that specific slide from the overview.
In any other scenario, this behavior amounts to breaking my back button, and I'll probably never visit the site again if I have that choice.