I believe they’re saying that antimatter functions, essentially, as a normal fuel (although an amazingly dense one, far surpassing the energy density of anything else we’ve ever used as a fuel). But it, ultimately, has all the drawbacks that are inherent to “normal” fuels.

But there have been proposals for other ways of traveling through space, that involve manipulating space itself, so the distance between point A and point B are smaller. Think of wormholes, or similar. One such proposal is the Alcubierre drive, which warps space around it to cause the total distance traveled to get from point A to point B to be much smaller.

But such exotic drives require exotic forms of matter that we have no evidence of