"Is your second paragraph really true?" Partially, on a PC. The difference, on a PC, between a high end NVMe SSD and a SATA SSD is minimal for most use cases;

"Is your second paragraph really true?" Partially, on a PC. The difference, on a PC, between a high end NVMe SSD and a SATA SSD is minimal for most use cases; small enough that an average user won't perceive much difference. The workloads in question (booting, loading a program, compiling code, etc.) involve a lot of operations that aren't bound by IO performance (network exchanges, decompressing textures, etc.) and haven't been optimized to maximize the benefit of high performance storage so the throughput and IOPS difference of the storage device don't entirely dominate.