Why is a woman allowed to travel for leisure, but not allowed to travel for Umrah, despite the availability of safe companionship and her yearning to visit the Sacred House of Allah?

Scholars differed regarding the condition of a mahram (unmarriageable kin) for a woman in Hajj and Umrah. The preponderant opinion is that it is not a condition for obligatory (Hajj/Umrah), so she may travel without a mahram or husband; rather, safe companionship suffices, such as the presence of trustworthy women, because it is an obligatory journey for which a mahram is not a condition. Ibn Taymiyyah held the view that it is permissible for a woman to travel without a mahram for any act of obedience if she is with companions and is safe. However, her travel for leisure is not permissible except with a mahram.