For the most part that duro in that size only works well and sells in slalom. I don't really think anyone would want to get around on 86a Inheats as it holds no real benefit compared to their other duros. Some people might use the 4pres, but again is it better than the alternative for the purpose.
If they created a 78 or 77 duro they would sell more of those than 86a.
In Abec11 BigZig world for every 100 sets you sold:
10 would be pink 77a
70 would be lime 80a
18 would be yellow 83a
2 would be orange 86a
In Zigzag world you sell a slightly better percentage of the non-lime duros