This is a category gap, not a feature gap.
One display versus a full multi-monitor rig
The Anker 555's single HDMI port caps you at one external 4K
display. The CalDigit TS4's three Thunderbolt 4 ports support
dual 6K displays or a single 8K display, which is the entire
reason it exists: it runs a multi-monitor gaming and WFH desk
from one cable to your laptop or PC.
Port count reflects two different jobs
8 ports covers a charger, one display, and a couple of
peripherals, enough for a hub that travels. 18 ports on the
TS4 covers multiple displays, external drives, audio interfaces,
wired ethernet, and peripherals simultaneously, without hunting
for a free port. If you're not using most of those 18 ports,
you don't need the TS4; if you keep running out of ports on a
multi-monitor desk, that's the actual signal to upgrade.
Speed only matters if you're moving real data
Thunderbolt 4's 40Gb/s is four times the Anker's 10Gb/s USB-C
ports, but a mouse, keyboard, or webcam uses a tiny fraction of
either. The gap matters for external SSDs, capture devices, or
anything genuinely bandwidth-heavy, not for a typical MMO and
WFH peripheral set like the ones covered in the
OSRS setup hub.