That depends very much on the workload. Four hard drives can deliver in aggregate a sequential bandwidth that exceeds any one consumer SATA SSD, or the sustaine

That depends very much on the workload. Four hard drives can deliver in aggregate a sequential bandwidth that exceeds any one consumer SATA SSD, or the sustained write bandwidth of most consumer NVMe SSDs. But when people are discussing IOPS, the usual implication is that they're talking about non-sequential access of relatively small block sizes. For those workloads, the difference between consumer SSDs and hard drives are still measured in orders of magnitude. So, what workloads did you have in mind when you said "generally"?