Why doesn't Hamas unite with West Bank's Fatah for their common goal instead of maintaining political divisions?

Dr. Mustafa Barghouti said in this video:

The Palestinian-Palestinian conflict and the internal division are caused by two things. Both are not ongoing right now. The first reason is the Oslo Accords (check the answer to the question Was the Oslo Agreement / Accords a mistake?. The disagreement on the Oslo Accords and the disagreement on the national approach. The supporters of the Oslo accords believe in the negotiations and some of them still believe in the middle solution with the Zionist movement, while Israel presents evidence every day to reject any idea of a middle solution. In my opinion, after what happened and after what Israel and Netanyahu did to destroy the Oslo Accords and the expansion of the settlement to 750,000 settlers, and after his continuous declaration that he will not allow the establishment of an independent Palestinian state, the reason for the political conflict vanishes, because those who believe in the Oslo accords have no one to talk to, there is no room for negotiations. Therefore, those who insist on the continuation of the Oslo Accords are wrong. Today, national unity must be established on a different program, a national struggle to overthrow the occupation, apartheid, and the racist separatist regime, as well as all of the occupation systems. So the division on the program has practically disappeared, even though some still hold on to their Oslo accords illusions in the Palestinian Authority.

The second reason for the division is the conflict over the authority in Gaza and the West Bank. This reason has also disappeared because there is no authority left. Israel has eliminated every authority. The authority in the West Bank has become an authority without authority and under the occupation, and Gaza is undergoing re-occupation as we see today. Therefore, what do we argue about? There is no reason for the division in the program because there is now no room for a program except for the national resistance and struggle. And for the authority, there is no authority because it is all under the occupation.

Therefore, in my opinion, there is no reason for the continuation of the division. Now, everyone should unite in a united national front. I mean a united national leadership for the Palestinians. The liberation Organization can be the backbone or platform of this united national leadership so that all the forces are included, including the Hamas movement and the Islamic Jihad movement, and so that there is no longer an individual decision from any party or party. I mean a united national leadership where everyone participates. For example, we have been members of the Liberation Organization since 2015 but we are not in the leadership of the Liberation Organization, we are marginalized from the leadership of the Liberation Organization. What should happen is a united leadership that includes everyone and agrees on a vision and a national program of joint struggle and resistance. It is possible that a temporary national unity government in the current situation to prevent the separation of Gaza from the West Bank to prevent the Israeli conspiracy to re-occupy Gaza and impose a convoy of agents to work under the supervision of the Israeli occupation to separate Gaza from the West Bank and to close the road in front of the United States and Israel in a policy of “divide and conquer”. Why do I say a temporary national unity government? Because, of course, in the current stage, it is difficult to run elections while the war is ongoing. After things calm down and we end this aggression, InshaAllah, and the reconstruction process begins, a temporary government in a period of no more than a year may call for elections. We will achieve what we should have done in 2011, which is to hold free and democratic elections and give the Palestinian people the right to choose their leadership in a democratic way. When people elect, they do not only elect people, they elect a method, a political program. In my opinion, there is no good program for the Palestinian people but a national resistance, struggle program.

I proposed that in front of the leadership of the brothers of the Fatah Movement and in front Brother Abu Mazen and the brothers of the Hamas Movement and others. I believe that there is a kind of coalition of a large number of the Palestinian forces on this vision now. The divisions still exist but the reasons no longer exist. But there are external interventions and some external interventions try to deepen the division in the Palestinian sphere. This hurts us. We must maintain the independence of the Palestinian national decision regardless of any external interventions to ensure that we have a unified national leadership.

I do not know what the disagreement is. Today, the Palestinian people are exposed to a second Nakba. There is no justification or reason to continue an internal conflict when we are in a real battle that threatens the lives of all Palestinians, not only in Gaza but also in the West Bank.