This is from Robertson's introduction to the first edition of W.H. Davis' Beginner's Grammar of the Greek New Testament (newly revised by Dr. David Shackleford and published in print by Wipf & Stock and available electronically in Logos Bible Software). Robertson wrote the forward to the first edition for his former student and friend, William Hersey Davis.

If one gets it into his head that the root idea of tense is time, he may never get it out and he will therefore never understand the beauty of the Greek tense, the most wonderful development in the history of language. (Davis, vii)

The idea that time is not the "root idea" of Greek tense is not new. The above is dated back to 1923.

I suppose it's the degree to which time plays a role in tense is what Porter, Fanning, McKay, Decker, Campbell, Silva, Caragounis, et. al. are bickering about.