Why aren't there 600MB/s SSDs on the SATA/USB port?

[williamcll]

The theoretical speed of USB 3.0 is 625MB/s and SATA3 can up to 750MB/s so why aren't there any drives that reaches this speed and instead everyone doubles the speed to NVME instead?

[Sakkura]

SATA3 uses 8b/10b encoding, so the theoretical usable bandwidth is only 600 MB/s. The fastest SATA SSDs can do 550 MB/s or a bit more, which is the practical limit. USB3.0 also has 8b/10b encoding overhead, making the theoretical usable bandwidth 500 MB/s. Since USB is a more versatile interface, it has some design aspects that can hamper performance for storage use, so you'll have an even harder time approaching that 500 MB/s limit in the real world.

[Pixel5]

20 hours ago, williamcll said:

The theoretical speed of USB 3.0 is 625MB/s and SATA3 can up to 750MB/s so why aren't there any drives that reaches this speed and instead everyone doubles the speed to NVME instead?

you said it yourself its the theoretical speed you could push via this port and cables but you also have overhead while transfering files which also takes some of that bandwidth.