A mark of 93 pulled down to 86 is a complete lie whoever told you that. You can go look at many of the ATAR calculators and if you get a 93 in business it corresponds to around 97-98 ATAR. The scaling is not too bad. It's definitely not as high as subjects like chemistry and physics but it's not completely bad. I did business studies as one of my subjects and still ended up with a high 99 ATAR.
An important point you are neglecting and probably your friends/people you know are telling you stuff, is the difficulty of business studies vs chemistry or physics as an example. Business studies is a subject that is quite easy in terms of the content basically anyone can understand it because a lot of the things are common sense type things that are intuitive. So you don't even have to be academically gifted to get a band 6 in it as just by working hard and following the syllabus in your study you can get high marks, as the questions don't really vary that much in difficulty or things they ask. This can sort of make the business studies subject boring which I found it was but beneficial in the sense that good preparation will always lead to a good mark. You might make the point that there are essays so the subject will favour people who are good at essays, however, the type of essays in the business studies are very different to English and commonly have a fixed kind of template you should follow to get good marks each time.
Chemistry and physics on the other hand will favour a certain type of student who is more geared towards problem solving and are more difficult in terms of how much content there is and questions that have a lot application of the content rather than just repeating facts and memorised things like business studies. This makes the subject challenging for the average student who isn't gifted in the sciences. As a result without a lot of work and dedication it becomes difficult to even get a high band 5 for a lot of students. So in the end it ends up sometimes being worse than having done the business studies and getting a higher mark.
So in summary no it doesn't really mean you are screwed doing business studies, the HSC is about playing to your strengths which depend on every student so that is what you should be choosing your subjects based on, as well as what you want to do in the future
Business studies aligns pretty well then scales like shit. So realistically it’s a 88 raw to a 92 reported mark by NESA to a 83 scaled used for calculating ATAR.
Scaling shit just means it’s an easy subject. Could be good, could be bad. High scaling subjects only really pay out if you can score around the same on them as you would in easier subjects.