Why did the Oslo peace Accords fail and who deserves the blame ?

They failed due to multiple reasons:
  1. Israeli leaders never accepted the creation of a genuinely independent Palestinian state as part of the two-state solution, continuing to colonize Palestinian land and deepen their control of Palestinians in the occupied territories while supposedly negotiating an end to the occupation.
  2. The hardline positions of successive Israeli governments were supported by the Clinton administration, and subsequently the administration of George W. Bush, which both failed to do anything to stop settlement construction or other Israeli violations of signed agreements and international law. Instead of serving as an honest broker, the US acted as "Israel's attorney," in the words of longtime senior US State Department official Aaron David Miller.
  3. The direct bilateral negotiations framework of Oslo accentuated the massive power imbalance between the two parties, which was further reinforced by the failure of the US to act as an even-handed mediator.
  4. While massively expanding settlements and attendant infrastructure such as Israeli-only roads on occupied Palestinian land, Israel began to place severe restrictions on Palestinian movement, both within the occupied territories themselves and between the territories and the outside world. Rather than gaining their freedom from decades of Israeli military rule, during the Oslo years most Palestinians instead witnessed a deepening of Israel's control over their lives and their land, causing widespread frustration and disillusionment with the peace process.
  5. A close examination of the agreements comprising the Oslo Accords and Israeli actions on the ground, most notably rapidly expanding settlement construction, indicate that Oslo was intended by its Israeli and American architects to cement Israeli control over the occupied territories while shifting responsibility for policing the Palestinian population from the Israeli army to the security forces of the PA.
The successive Israeli governments deserve the blame.