The BBC news report mentioned there had been previous tail damage from a bad landing, but the Russians insist the damage had been repaired. If they are wrong, a malfunction in the tail could perhaps have caused the aircraft to dive until the stresses exceeded the design specifications and disintegrated the aircraft with a separation of the tail section.
The problem with modern Airbus and even Boeing constructions is the use of non metal composites in the airframe. When I was in high-school studying to get my airframe and power plant vocational license the old timers used to tap on the metal and could tell if there was metal fatigue by the sound the metal made and then they could do a whole host of electric spectrogram tests (as best I can remember) on the metal. You can't really test these composites for cracks. A failure of such a composite material caused the crash of that airline in New York shortly after 9/11. It was a coincidence that it happened so near the terrorist attacks and it happened on take off and not at 30K feet but it could be that. There is a big argument going on in the maintenance industry over the switch to composite vs metal/aluminum.
Another crash due to improperly-repaired tail-strike damage:
https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123