From the user point of view nothing should change in normal conditions, as well as for normally behaving sites. thus I don't think it's necessary. This is just some precautions against misbehaving web sites.
Bug 1915404 Comment 5 Edit History
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From the user point of view nothing should change in normal conditions, as well as for normally behaving sites. ~thus I don't think it's necessary. This is just some precautions against misbehaving web sites.~ After discussion, let's put up a note as an heads-up.