The bandwidth-delay product is a limitation of physics so you can't exactly "overcome" it. But because QUIC is implemented in userspace instead of the kernel,

The bandwidth-delay product is a limitation of physics so you can't exactly "overcome" it. But because QUIC is implemented in userspace instead of the kernel, assumptions the kernel makes (like "the bandwidth-delay product will never be >= x") can be avoided in a cross-platform way, allowing for interesting, low-cost experiments that can later feed into improved TCP implementations (which take much longer to deploy).