This is very much nitpicking and I intend to post this only for informational purposes.
HTL means Hardware Transformation and Lighting which debuted with the very first GeForce and Radeon GPU's back in 1999/2000. Retail FS2 did not support HTL, but once source code was released one of the first major improvements was to add HTL support. Added rendering performance allowed hi-poly models, hi-res textures and hi-res effects just as it allowed other eye-candy. However, HTL and hi-poly never have and never will mean the same thing.
And no, I do not expect this post to change how the term is used here in HLP. Just as long as you realize that nobody uses HTL as a synonym for hi-poly outside of HLP and even here it is purely by association.