TFA means "the featured article", so in this case the "Why wordfreq will not be updated" link we're talking about.
It’s the same origin. On Slashdot (the HN of the early 00’s) people would admonish others to RTFA. Then they started using it as a referent: TFA was the thing you were supposed to have read.
I miss the old Atomic MPC forums in the ~00s.