And in their test, they made writes at that frequency, right?

It is, however, commonly used for average frequency rates too, not just measurements of constant frequency. "Frequency" the word means how frequent something happens, right?

I don't know what the 'something' to measure frequency of in pink noise would be, but if there is something to count over time, you can measure it's frequency.

"Frequency is the number of occurences of a repeating event per unit time" says wikipedia. https://en.wikipedia.org/wiki/Frequency

However, it is true that "In some fields, especially where frequency-domain analysis is used, the concept of frequency is applied only to sinusoidal phenomena, since in linear systems more complex periodic and nonperiodic phonomena are most easily analyzed in terms of sums of sinusoids of different frequencies." In some fields.

I have no idea why we're arguing about this except that we like arguing on the internet though.