Of course it's possible but it's definitely harder - I say this from experience. I was aiming for a 99 and just fell short (98.65) and all my raw scores were above 40, including higher 40s (overall after scaling my scores should be something like 48 46 45 44 42 + uni increment). While I'm not saying "I deserved more" or others deserved less or whatever, I did see scaling benefiting A LOT of the high achievers at my school. All the 99s at my school (a select entry school) included people who either completed specialist maths or a language (except for one girl who's crazy and dominated all her science subjects). A lot of these people did get <40 in some subject(s). The higher 99s however, definitely had either spesh or a language.
I'm not saying you NEED a super scaling subject to get high 99s, it's just that 99 without scaling subjects really is, to an extent, harder - I know scaling is supposed to make things even but it's not COMPLETELY even unfortunately. But it's not something we should complain about either, cos what can they do haha. I still stick by the "pick subjects you like" because while I did not get 99, I REALLY REALLY enjoyed Year 12, it wasn't as stressful as Year 11 (where I took methods and hated it lol) and I still get into my course so there's not much to complain about really! I think for me, it was the simple act of aiming for 99 that did me justice, even if I didn't quite get it. It was enough to get me through, but just low enough to supply me with some crazy drive to own everyone in university to compensate... LOL
So GO FOR 99! But if you don't get it for some reason, don't think it's because you're incapable!! Yeah that's my point, I was wondering where I was going with this. I know people want to hear stories from people who got high 99s without scaling subjects but you should look at both sides I guess?