I use d3 BS1 all the time with great results, but it isn't difficult to react to and block if you know what you're doing.
If you get hit by d3 then just blocking is the best response. Killer might hit for another d3 for 2%, but in all likelyhood he's going for BS1 at some point. Once BS1 bounces of the block, Killer loses his pressure advantage. Killer can try to go low with s3 or bf3 after d3, but both are very slow.
If they decide to just block low Killer has the option of bs2, but releasing crouch is easy at the range d3 pushes them back on block, and then it is an easy punish.
Again, I'm not saying d3 BS1 is a bad tool at all, I use it all the time. I'm just saying that there are fairly simple and quick counters to d3 as there are only so many things Killer can do out of it. If they know to just block once hit by d3 the options really dry up, and can be heavily punished to boot.
The thing is, most people react to d3 by blocking, which just happens to be the best response. It's not that d3 bs1 is weak, it's that the quickest and most natural response happens to be the best one. If you get hit by one d3, block low and you will block the next move 90% of the time.
Huh loses the pressure advantage? At one point every characters lose "pressure advantage" (Thanks GOD).
1st Killer's doesn't have a real pressure anyway but he has that mind game that is really strong.
2nd You Can make everything safe with BS1 -8 with the best (or almost) pushback in the game.
3rd Killer is one of the characters with the best neutral game, situation gave by BS1.
4th Here is the thing, you can almost whiff punish every moves after BS1 just holding back and pressing F1 ; if your opponent loses just even 1 frame you can get the pressure back with F1/ BS1/ BS1 cancel into whatever you want (D3 being the fastest move, BS1 again to get back in the neutral game).
5th I've never said that D3 BS1 was connecting but I can assure that it is impossible to react to BS1 so if your opponent get hit by D3 and block BS1, then yeah I'm ok (What else so you want? You're back in the best state for Killer : Neutral game!) , but the most important happens when your opponent blocks that D3!
Mate, please, record your games and post it. Anyway it is a fighting game : "Reads" , "Answers" , "Highs", "Pokes"... They exist for both player (in general pokes are the fastest moves and the perfect answer to highs), you're not alone during your games -_-
If you are trying to respond to a -5 move by your 7high and your opponent reads it, then the character doesn't have to be blamed, you should blamed yourself especially if it happens everytime and you don't get that yet.
Anyway it has no point to argue on that here and I only labbed Leatherface 3hours and did 11games with him so I guess I'm wrong