Bulges fail to behave like merger products: pure-disk massive galaxies are common despite predicted merger histories, and existing bulges are often decoupled from their disks in kinematics, age, and structure, as if the two components had separate origins (Kormendy and Kennicutt 2004; Kormendy 2010; Brooks and Christensen 2016).
Hierarchical assembly makes bulges the residue of the merger history that built the disk, so the two components must be interwoven: bulge mass should track merger count, and bulge populations should interleave with disk populations. Frequent-enough mergers to satisfy halo statistics cannot leave this many disks pure and this many bulges foreign to their disks.
SCT separates bulge and disk at the source. A galaxy's structure is set at the seeding epoch by the angular momentum its formation deposit carried (P31, P32): the deposit's high-J material settles into the extended disk behind a centrifugal barrier, while its low-J core condenses into the central concentration. Bulge and disk are then two angular-momentum settings of one deposition event, not cause and consequence of a merger history, which is exactly the observed decoupling: separate kinematics, separate population clocks, structural parameters free to vary independently because nothing ever required them to be built by the same process.
Pure-disk galaxies fall out as the high-J tail: a seeding event with large impact parameter delivers little low-J material, and no bulge ever forms, with no feedback conspiracy needed to suppress it. Pseudo-bulges with disk-like kinematics are the intermediate setting. This is the same seeding-epoch morphology principle, structural type fixed by the J/J_circ ratio and preserved by exact conservation, that carries the high-z grand-design spirals, the morphological constancy to z of 10, and the ring galaxies (recid 104); bulge-disk decoupling is its two-component reading. The morphology mechanics are in Paper 4, From Chaos To Collisothermal Cosmogenesis, Section 3.3, with the inheritance formalism in Paper 5, From Chaos To Corotating Hierarchies.
Keystone economy: P31 splits the deposit by angular momentum, P32 keeps the split. Mergers still happen; they were just never the bulge factory.
JWST and Euclid structural censuses carry the kill: if bulge properties correlate tightly with independent merger-history indicators, tidal features, stellar halo mass, kinematic disturbance, across large samples, the merger-built-bulge picture stands and the seeding split is unnecessary. SCT separately requires pure disks to exist already at high redshift in their late-time proportions; a bulgeless fraction that grows toward late times, tracking quiet merger histories, would favor suppression over seeding and refute the M3 reading.