Why isn't tackle for a loss an official stat?

[R.E.N. Spells Ren]

Sacks have been tracked officially for over 3 decades, what's taking them so long to officially track tackles for loss?

They're nearly as big plays as sacks and deserve recognition over regular tackles, many of which follow big gains.

 

[Carlos Huerta]

No se, man..

I was actually thinking about the sack records yesterday and wondering why they can't just go back and look at all the footage from Deacon Jones' games and add 'em up?