Together with the lack of copyright transfers, it just guarantees the code will always be available under the same license. There can't be any re-licensing of existing code without twisting the arms of every single copyright holder. No more, no less. It gives nobody an exclusive control point. It gives nobody exclusive rights to exploit.

So, yes, Amazon can spin up as many matrix servers as they want. And so can MS. And so can Google. Maybe that wouldn't be such a horrible idea as they have mutually incompatible products that loosely overlap with the matrix feature set; those things interconnecting would be progress. Email is doing pretty OK decades after MS tried to embrace and extend via outlook and exchange. Federated communication networks are nice.

So, that's a feature not a bug.