I don't think learning the fundamentals before branching out into more specialist areas is such a bad thing. I'm not sure how 10th Planet works these days, but I know Eddie says his beginner classes are focused almost solely around the warmups (which, I imagine, look very similar to most BJJ Fundamentals programs). The problem I've seen with people who want to base their game around Rubber Guard too early is the same with those - I was one, by the way - who try to base their game around Triangles too early. They get very comfortable off their back, which is fine - but it stops you learning pressure and balance and the many other areas of Jiujitsu.
I used to play almost purely Rubber Guard and Triangles to the extent I'd be pretty happy being taken down. At White Belt I was winning golds at nearly every competition I entered... As soon as I stepped up to blue / purple level competitions (although, technically, I am still a white belt - I don't have anyone to grade me) I was losing on points in the first round. I'd get taken down, I'd get guard and be sure I'd Triangle / Invisible Collar my opponent. Didn't happen. Blue Belts know how not to get Triangled by White/Blue Belts. A lot of Blue Belts don't make getting Invisible Collar easy. If they train at a 10th Planet school it will be even harder. It took a good year to 18 months of work to catch up and fix things and begin winning medals again.
The most important piece of advice I ever got was from Eddie through MTS: 'Do not be the Triangle guy', but I think that extends to anything - don't be the guy who relies on 'X'. Be the guy who is good everywhere. Follow the curriculum until you are awesome at the basics - keep working your Rubber Guard, etc, but do it with the lower belts and your friends. Once your fundamentals are solid start playing with new stuff. Once the higher belts know you have a solid base they will expect you to begin looking for new techniques.