All those that top out in the mid 80s are not equal. Perhaps another way to look at it is to figure out how many 90+ are not recruited by DI colleges? How many mid 80s are not recruited by DI colleges? So academics not considered, pretty much all the 90 guys will get DI offers. Most of the mid 80s guys will not get a DI offer, but many will.
Also keep in mind when we see a DI pitcher topping out at 86, it doesn't mean that is all he is capable of. Often pitchers throw below their max velocity in order to gain command and movement. So there are college pitchers throwing in the mid to upper 80s that we saw throw 90 or better while they were in HS. The more velocity a pitcher can throw, the more room he has to subtract and improve in other areas. The less velocity a pitcher can throw, subtraction can have a negative affect. The guy with great velocity simply has much more to work with. Doesn't mean the mid 80s guy can't be successful.