When did LTN and Sub5 become mutually exclusive to each other?

[IHATEINDIANS]

Seems like a new grey thing, I see a lot of people in comment sections and even here refer to 3/10s and below as "Sub5s" but 4/10s (LTN) as just... LTN, rather than LTN + Sub5.

Sub5 literally means anything below average (5/10). LTN is below average. Subhuman is farther below average. Why did they become mutually exclusive? All LTNs are sub5s, not all sub5s are LTN.

 

[Nectar]

The rating system is bs this is why numbers alone are more accurate
For some MTN can mean anywhere from a 5 to a 7…

Check out faceiq he does it right