Maybe in theory but in a real listening room you can easily locate a subwoofer that is crossed at 80Hz.
Which points to the 80Hz LFE crossover, being one driven by marketing/sales, rather than the actual margin of audibility for directional bass...
And really, the main channel speakers need to go down to at least the limit of directional bass.... so a 60Hz or 50Hz bass extension is what is needed in the mains .... Full range mains are the real solution, with subs suplementing the bottom 2 or 3 octaves only... say 15Hz to 60Hz... also subs designed for the lowest frequencies, tend to not do so well at the higher end of the bass range... so limiting them to the range they do best is optimal that way too!
And once you have them down at that low end - is there a point to directional bass?
But if you have a bunch of satelite speakers, as many do, with bass extension limited to somewhere between 60Hz and 120Hz ... and the subs have to fill in the gap up into the range where bass is directional - then Directional bass with subs is very useful.... but it seems a fundamentally flawed paradigm.