That's similar to what Immortal and Darkthrone did, except for them it was constant ambient drumming. This cut guitar free from drums, which enables more rhythmic variety.
The aim of Darkthrone is different. Eucharist is a Death Metal band, I don't think the solution for making the guitars and drums independent of each other is to relegate the drums to a machine-like function. I think that for simplicity, they are disconnected. Not because Eucharist is providing a clear refinement superior to At the Gates' use of percussion.
I've been practicing Kingdom Gone during this last month and I've noticed how effectively the drums are used in relation to the guitars to this effect. If anything, this album provides a template for freely flowing instruments that nonetheless coalesce to form a solid whole.
What happens in TRITSIO, and the reason why it is a step up from the demo, is that the drums take on a role as important as the guitars rather than a mere complement. The guitars and drums are only tied in the sense that they must match beginnings and endings. Other than that, the drums are used effectively to bring dynamics to the music. Next time you guys listen to the album, try and make out how, when and WHY the drum patterns change in relation to the riffs. You'll notice that the patterns and changes in the drums take the front seat when the guitar riffs repeat or use more same-length notes, specially when at a slow speed. And the drum pattern will become flatter and less jumpy when you have guitar riffs that introduce more rhythmical variety. But the same exact feeling is never allowed to linger for long, thus you are never stagnant. At the same time the overall idea is preserved clearly and if you are paying attention closely you'll noticed it is never really broken into unrelated random riffs.The biggest divergence happens with transition riffs which are like taking in a breathe between two sections.
Right at the beginning of Kingdom Gone, for example, the same riff is repeated by the guitars 4 times, with one guitar strumming 2 chords as the other one repeating the first and main expression of the motif over each single chord. What happens in the drums is that for the first 2 instantiations of this riff, it plays a simple pattern on the toms, for the second pair, it plays a second pattern involving mid-paced double bass and the snare that makes this sound more crowded. When the 5th repetition arrives the guitar which was playing chords joins the one outlining the motif one time, on the 6th repetition the drums change again to a pattern that releases the tension of the previous pattern and one of the guitars plays the motif a fifth(interval) higher than the original pattern only to return to a unison for the 7th repetition of this riff.
This is only the beginning, this sort of patterns and non-conformity with the application of classical binary form with very smooth transitions is found throughout the whole song in different ways.
This first part I described is what I would call section A. They often use this "da capo aria" form ABA', where the A' is obviously an incarnation of the A section but also noticeably a variation of it, with At the Gates providing the variation by providing a different "tale".