This is a benefit of eSATA compared to USB, since USB has to be compatible with other functions like mouse, keyboard, charging, etc. By using eSATA, PC’s motherboard just deals with one drive at a time, while with USB, it deals with multiple devices simultaneously.
eSATA was the fastest interface (1.5 to 6 Gb/s) on PCs, before the appearance of USB 3.0 and thunderbolt (10 Gb/s). It is worth mentioning that the read speed of eSATA is the half of USB 3.0, while write speed in eSATA is twice faster than USB 3.0.