Thats not your "normal" AR collapsing stock. These are more in line with whats normally used....
I just checked the basic sliders (like the second stock in the above links) on my Armalite and Bushmaster, and they measure 10" collapsed, and 13.5" extended. I also checked the LOP on my one Armalite that has an A2 stock on it, and it measures 13.75".
This might be plausible if you have a naturally shorter LOP. However, most of us are not shooting with armor.
Do you hunt or shoot realistically, be it "games" or for other reasons? If so, you know why the shorter LOP is desirable.
I dont have a short LOP, but I do prefer long guns with stocks that have a more military or traditional (pre 60's) LOP, as thats what I learned to shoot with. I dont normally shoot off a bench, and shoot more realistically from field and improvised positions. Rifles with extended LOP's tend to make doing so more difficult, as youre fighting the gun trying to get it in your shoulder. Add a layer or two of clothing and/or gear, and it just gets worse.