No, it doesn't go against the whole point of the Sicilian Defence. There are quite a few different ways white can play against the Sicilian, and that one (2.Nf3 followed by 3.d4) is aggressive but also quite tricky to handle, and white has to know a lot of different systems black can choose. So that way is very popular at high levels of the game but much much less popular at lower levels (say below 2000).
Besides the plan with 2.Nf3 and 3.d4, white has at least the following plans:
- c3 followed by d4. The point of 1.e4 was to follow up with 2.d4, 1...c5 stopped that, white continues with his plan. After 2.c3 black can either lure the e-pawn forward with 2...Nf6 3.e5 Nd5 or exchange it with 2...d5 3.exd5 Qxd5.
- A closed system with the pawn move d3, where white is happy with his d3/e4 center and aims for an attack on the kingside, often including the move f4 at some point. There are many different versions of this plan, 2.Nc3 first of all stops ...d5 and is probably the most popular, after that white can put his bishop on g2, c4 or b5, play d3 and f4, etc. 2.d3, 2.f4, 2.g3, 2.Na3 lead to other variations on this plan.
- Nf3 and Bb5, usually aiming to weaken black's pawn structure with Bxc6 and postponing the decision to go for a c3-d4 or a d3-e4 center.
- Independent lines like the Morra Gambit (2.d4 cxd4 3.c3) and the Wing Gambit (2.b4).
Basically, White is White and he has a huge array of different options that you'll all need to get to know eventually. 2.Nf3 and 3.d4 is just one of many.
I'm quite new at chess and I've started to play the sicilian defence a lot more. The problem that I've encountered is when playing against someone that doesn't trade off their centre pawn for my c5 pawn. They just continue developing their pieces.
How do I advance from there? Do I just develop my knights and bishops normally? Doesn't not trading for my c5 pawn just go against the whole point of the sicilian defence?
Thanks in advance.