Ribbon mic question

Hi, I recently came upon this thread
Ribbon mic (DIY) - Bigger gap to shorten front to back path. | GroupDIY
where PRR mentioned that the magnetic strength of a ribbon mic can affect whether it is resistance driven or mass driven. But it was my understanding that magnetic strength only affects the sensitivity.

If X amps are being run through Y magnetic field, the effect on the ribbon should be the same regardless of X and Y as long as X is sufficient.

So why did PRR say that the magnetic field can negate the effect of mass on a ribbon?