The Arab League has instructed that Palestinians living in Arab countries should not be given citizenship to avoid dissolution of their identity and protect their right to return to their homeland.
It seems that as long ago as 1959 the then United Nations Secretary-General put forward proposals aimed inter alia at actively involving the refugees in the socioeconomic development of the Middle East at large and the wealthy Gulf states in particular. The Arab League rejected these proposals for they saw them as an indirect means of depopulating the camps and burying the right of return. It also argued that the socioeconomic development of the region should not be linked to the settlement of the refugee issue. On their part, the 45 representatives of nine refugee organisations based in Lebanon also rejected the proposals...
That rejection included the no citizenship granting in this decision: see page 88, note 129:LASC/RES/1547 (531) of March 9, 1959
Its content also described thus: Resolution 1547 of 9 March 1959, which encourages Arab states –– as a general rule –– to preserve the Palestinian nationality of the refugees... in a publication entitled: Rights in Principle - Rights in Practice, Revisiting the Role of International Law in Crafting Durable Solutions for Palestinian Refugees, Terry Rempel, Editor).
No Arab country will therefore grant citizenship to "Palestinians" who live in their country and in some they are not even allowed to join professional organisations thereby barring them from pursuing a career in law, medicine etc. That is not the case in Israel but the BDS crowd will not tell you that.
The Arabs have therefore decided to perpetuate the wretched conditions of the "refugees" solely as a political tool against Israel. Another instance of the Arabs hatred for Israel overriding their love for their own.