Doing this would defeat the purpose of selling EBCI. The whole point of that is to encourage people to pay for a better boarding number. If it only took $10 to guarantee six people on a single PNR an A or low B then there would be little incentive to buy it for more than one person.

Of course the SW policy of allowing people to "claim seats" for those boarding later pretty much defeats the value of EBCI also.

I suppose that it would be a nice elite perk if SW could find a way to let an A lister bring one person on at their boarding slot, but then you get the A lister who expects to board their family of 5 at that spot, etc, etc,etc

Same with BS buyers. One may be no problem, but then there is the one BS ticket with six WGA wanting to board at the A 3 spot.

And of course there is the issue that a late check-in may garner an A slot because someone canceled and their spot returned for use. THAT really devalues the whole process.

But SW will do what's best for their bottom line. I doubt they are going to alienate enough people with their boarding practices anytime soon.