Hot take incoming:
The ASM1166 isn’t as bad as claimed under SCALE. There was an issue with the driver quirk in the newer kernel where it would always report having 32 ports instead of the correct hardware count, but it’s not on the same level of “don’t ever use these.”
The potential issues regarding quality control of the physical card the chip is installed on remain though - as pointed out, the M.2 form factor ones are subject to a lot more torque from their connectors (especially the ones that use SFF-8087 SAS-style plugs) so a weak PCB will likely crack and result in bad/no contact internally - I believe a couple YouTube creators had this problem. The relative lack of airflow/cooling is a second factor, as a standalone PCIe card has a lot more surface area, so a larger heatsink can be used, there’s generally better airflow available in the PCIe section, and the cables are less likely to restrict what airflow is available.
We had a rather long discussion here about them, I’ll link to my post which was marked as the “Solve” and I feel summarizes things pretty nicely.