So what you are talking about are the brigades, they are a secondary level of approval overseen by the Brigade Team.
You cannot be approved into the brigades until after your kit has been approved by the Approval Team and you have become an OM (Offical Member). You can build with the requirements in mind of a brigade profession. But like I said brigade approval is a next step after approval by the Approval Team and it is also in no way required it is just something one can do if they so choose.
The reason the advice is to focus on the basic CRLs is because the brigade requirements or BRLs are an optional second level of standards that one can build towards, but once again they aren't required. Nor are they required to say that your character is as in your case a sniper, they are merely another level of build that you can choose to challenge yourself too.
Having your kit approved as a brigade kit is a personal achievement, it is not something that anyone is required to do. Until the CRLs which every offical member is required to meet and follow.