What makes music so congested?

See if you find a British original LP of that and see if you still say the same thing (Atlantic 'Plum' label). The mix is OK FWIW, though its not going to be as spacious as many jazz LPs, its pretty standard fare for the period. Its not likely IMO that the CD is going to show any of that off.

If all sound is poorly portrayed,it sounds like you need more definition in your system. Ampr? Speakers? CD player? Cables? Probably it is all contributing...or perhaps you need to put your components on spikes, or other resonance control devices. Try different things you could borrow before buying.

Remastered US CD from a few years back is good to average or above average depending on track as I recall.

Need not sound overtly "congested" though often does from what I have heard over the years. So devil is in the details as usual.

Not uncommon for many small ensemble jazz CDs to sound relatively uncongested more often on more typical rigs than for many progressive rock albums, like Fragile, which are typically more of a challenge for a rig to relate cleanly.

If you are able to get a mixed bag recording like Fragile (even the original CD master) to sound clean end to end, most everything else will as well, but not vice versa.

Relayer is another Yes album , TGOD in particular, that is very challenging. I've had it on vinyl and CD since it first came out on each pretty much and only recently was I able to squeeze everything out of one of the more recent CD remastered versions. THe original vinyl always sounded pretty decent but all CD versions I have heard are a real challenge to surmount! If you get to the point where TGOD on CD, the battle sequence in particular, does not sound overtly muddled and congested (it is doable) you are then sitting pretty for most anything to sound at least decent. It's a pretty telling acid test CD not as a reference recording by any stretch but as a test of your rigs ability to decipher and deliver the music in the recording coherently.

TGOD is a 20th century rock music masterpiece to me, a real spirit cleanser when needed, so getting it right finally has always been a priority for me.

I did a bit of research on the dynamic range of this Yes Fragile album. there was some info on a Head-fi.org forum by a person skilled in the art of mastering & there was some data on avaxhome.ws. In both locations the dynamic range of the various tracks on this album showed the range of DR12-DR10.
The info shared on the head-fi.org forum stated that tracks having a DR14 ie. a dynamic range of 14dB are likely to sound very nice & spacious. Those tracks having in the region of DR10 will sound very aggressive (due to the hard clipping of the waveforms at both the top & bottom ends thereby creating a lot of distortion).
I'm thinking that even tho' it might be your equipment the real reason for the congested sonics is that this album was compressed a lot during mastering to make it loud. You can optimize your equipment & speaker placement & that might help a bit but the source of the issue is the high level of compression in the source material. No way around this unless someone else remasters the analog tapes & we hope that the analog tapes were recorded with plenty of headroom.....

the head-fi.org forum link:
http://www.head-fi.org/t/492421/dynamic-range-of-cds-examples

One way to figure this out is to lower the volume and see if you get less congestion. Or, use decent headphones with your system, and see how it sounds. If either of these reduces or eliminates the congestion, the issue is probably in your amp and/or speakers. If the congestion remains roughly the same, it may be your source components and/or preamp and/or AC power.

I am not enough of a Yes fan to test it for you, but a recent speaker upgrade determined that, in my system, the speakers were absolutely responsible for congestion at higher levels.