Why pay for Thunderbolt 4 connectivity to storage devices when the storage devices typically can only use less than half of the Thunderbolt 4, or even other connection protocols?

What am I misunderstanding?

Thank you, in advance, for your time and assistance.

Why pay for Thunderbolt 3/4 (TB3 / TB4) connectivity on storage devices when the storage devices typically can only use half or less of the max TB3 / TB4's rated bandwidth?

This appears to be the same for the various USB protocols on storage devices, but with some devices seeming to "get closer" to the max rated bandwidth available.

In example:

Assuming:

1) TB3 / TB4's bandwidth is up to 40 Gb/s (or 5000 MB/s)

2) USB 3.2 - 10 Gb/s bandwidth is up to 10 Gb/s (or 1250 MB/s)

• aka: USB 3.2 Gen 2 (2x1) / USB 3.1 Gen 2's

3) SATA 6G's bandwidth is up to 6.0 Gb/s (or 600 MB/s)

(TB3 / TB4)

1A) OWC ThunderBay 4 mini (TB3):

• 2.5” SATA (6.0 Gb/s) SSDs &
• 2.5” 7200 RPM SATA (6.0 Gb/s) HDDs

• Real-world speeds up to:

• 765 MB/s for HDDs (of 5000 MB/s)

• 1556 MB/s for SSDs (of 5000 MB/s)

1B) OWC ThunderBay 4 (TB3):

• 2.5” SATA (6.0 Gb/s) SSDs &
• 3.5” 7200 RPM SATA (6.0 Gb/s) HDDs

• Real-world speeds up to 1527 MB/s (of 5000 MB/s)

1C) OWC Envoy Express Enclosure (TB3):

• NVMe PCIe 3.0 M.2 SSD

• Real-world speeds up to 1553 MB/s (of 5000 MB/s)

1D) OWC Envoy Pro FX:

• NVMe PCIe 3.0 M.2 SSD (TB4 ?)

• Real-world speeds up to 2800 MB/s (of 5000 MB/s)

1E) OWC Envoy Pro SX:

NVMe PCIe 3.0 M.2 SSD (TB3)

• Real-world speeds up to 2847 MB/s (of 5000 MB/s)

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(USB 3.2 - 10 Gb/s)

2A) OWC Mercury Elite Pro Dual mini:

• 2.5” SATA (6.0 Gb/s) SSDs &
• 2.5” SATA (6.0 Gb/s) HDDs

• Real-world speeds up to:

• 366 MB/s for HDDs (of 1250 MB/s)

• 989 MB/s for SSDs (of 1250 MB/s)

2B) OWC Envoy Pro Elektron:

• NVMe PCIe 3.0 M.2 SSD

• Real-world speeds up to 1011 MB/s (of 1250 MB/s)