Consider that Paypal is not accepted in a few countries from that continent, then you'll realize that there's a market for it.
The other side is Paypal is an American outfit. With options like Kudi that are not controlled from the USA, there's less chance of a group not popular with the US govt. being denied access to funds.
There are many angles to consider. You just have to know the landscape. And an aside: From my knowledge of that part of the world, kudi is Hausa for money.
The same argument can be made for "Alibaba for Africa".
Imagine if Alibaba was not founded, and the Chinese had to rely on Amazon. That's a lot of moving flowing from online Chinese shoppers to the confers of Amazon. At some point it becomes a national security issue.
So, yes, "Alibaba for Africa" makes a lot of sense.