I’m not sure you’re right about the original assertion.
But Islam is a decentralized religion.
Unlike Catholicism (Pope is the CEO), or the Russian Orthodox Church, or the Baptists, or for that matter, Orthodox Jewry, Islam doesn’t have anything like a central policy-making body that provides guidance on how congregations should behave.
Mosques and Islamic communities are largely locally autonomous, and they do their own thing without policy direction or funding from some national or international agency.
Finally, in my observation, Islam is more about prayer and obedience, than it is about service and welfare. (which is related to my first two points).
Sure, someone is going to argue that there are plenty of muslim organizations that provide services to others – that’s true – but on a far smaller scale than the other major religions.