Ah, it looks like we have a small misunderstanding. I thought you were talking about uncompressed video, which is enormous. This is only used in HDMI cables for example. A 1080p60 uncompressed video is 2.98Gbit/s, or about 1.22 terabytes per hour.

A remux is “uncompressed” in the sense that it isn’t recompressed, or in this case transcoded. A remux is still compressed, just to a lesser degree than a transcode. This means the files are indeed larger, but the quality is also better than transcodes.

To clarify the article’s confusing statement: they claim that remuxes can reduce size by throwing away some audio streams, while keeping the original video. This is true, but the video itself hasn’t gotten any smaller: you are simply throwing away other information.

It can save data by excluding data streams that you don't need. For instance, I don't need French, Italian, Japanese, German 5.1 audio streams that each have 700Mbps bitrates or higher, nor do I need an English 1.5Gbps master audio stream, a 700 Mbps English stream, a 500 Mbps descriptive audio for the blind, and 5 different special edition commentary tracks for a film I'll watch once or twice. All those tracks can really add up, and torrent sites are often country or language specific, so remuxes might have original language and/or native language audio only.