You can patent nearly anything but whether it stands up in Court or not is another matter, as many large organisations have found to their cost in the past.
Not quite true.
Apples lawyers abused the european legal system, designed to provide initial/temporary patent protection for minor companies or individuals, whilst they develop a product from a unique idea, and patented practically every possible screen and shape combination that has been released in a phone previously, or could conceivably be used for a portable device.
The loose requirements of the system meant that actual dimensions, ratios, capabilites, construction materials were considered irrelevant by the system, basically granting apple the capability of blocking practically every product by competitors.
Apple just chose to exercise the option against Samsung, because they were the strongest competitor to the IPhone.