mtf – What is considered a good / great LP/PH value?

After combing through ISO 12233 and reading multiple articles, I’m still unsure what LP/PH values are considered poor, good, or great. I just finished testing a Nikon D750 with an 18-70mm lens. I’m using Imatest to do the analysis. For example, I’m analyzing 9 regions of the sensor, and I’m getting values ranging from 486 LP/PH in the bottom left corner to 1261 in the center.
According to this page:

Lens MTF Test Info

30 lp/mm > 0.5 is very sharp
30 lp/mm > 0.3 is sharp if you sharpen a bit
30 lp/mm < 0.2 is getting soft

For a DX lens, the Picture Height (PH) is 16mm.
This results in (30LP/mm)*(16mm/PH) = 480 LP/PH.
This would suggest if MTF50 > 480 LP/PH is sharp.

However, on another forum, I saw a comment that said:

I find 1400LP/PH acceptable, but 2400+ preferable.

If 480 is very sharp, why would someone fine 1400 only acceptable?

Any assistance, reference, etc. would be .beneficial