Testing the SATA port multiplier with the MSI X570-A PRO resulted in the BIOS being unable to recognize the logic. Small wonder the low cost solution cannot find new markets. Supporting SATA port multipliers would boost sales of more hard disks and DVD/BD drives etc.
16-port SATA cards are not that much money and they can handle the HAF 932 loaded with front panel disk boxes. Less expensive 4-port and 8-port SATA cards are very popular. The Mini-SAS Connector (SFF-8087) on 8-port and 16-port cards is standardized so cables are abundant and low cost.
There are PCI cards available for older machines in addition to PCIe cards. Generally old machines are not as energy efficient which favors newer hardware.
To manage a smaller 4 disk panel box a low cost PCIe 2.0 x1 card can handle the workload. The Marvell 88SE9215 is very popular for ultra low cost SATA III hardware.
The 8-port and 16-port controllers need PCIe x4 slots. PCIe controllers can handle SSD bandwidth easily. Older model server controller are now being sold to consumers at very low cost but check specs closely to be sure the model is suitable.
The ICY DOCK Expresscage MB324SP-B has four pop out bays for 2½” disks. The trays have some pins to secure the disk for insertion. There is enough room for older 9.5mm hard disks.
The HAF 932 has six drive bays to it possible to install 24 hard disks. Unfortunately Windows would run out of drive letters for such a monstrosity. Larger storage units use software RAID to pool the disks with fault tolerance so 24 disks server are relatively safe. Racks of the machines are used by some studios for video editing etc.
There is such a diversity of front panel boxes available. One model had a front USB 3.0 beside the 2½” disk and it had a 3½” disk below. The 4 disk model allows more disks to be active.
The Marvell controller chips all support the port multiplier, so this suggests AMD is intentionally blocking their use. The same problem with an old Intel box.