There are so many possibilities of coding style now too.
Chris for instance has written some really nice things using pixel shaders, as well as lots of notable tiny productions, also there are the larger demos that use GL and Directx and there are also those of us who code for obscure platforms with sometimes obscure languages.
As you've seen, there is a massive blend of skills here and what sets this place apart from other forums is that we try and share our knowledge in a friendly way.
As for having a library of routines, and speaking only for myself I use other peoples libraries in my programs, things like Ufmod for playing music, a new framework that mimics Tinyptc but with more compatibility, features and steady refresh rate was developed mainly by Rbraz and Jim, those two things I would not do without, but then there are other things that you need to factor in..
Little things like your routine to open screens for instance, yoiu might write it once and then adapt it to suit everything else you work on, rarely re-coding it all.
As other people have said too, once you know how the effect is made, as long as you have a good grasp of the language you use, it's always possible to reproduce effects and hopefully adapt them into new ideas too.
If there are any particular things that you'd need to know how to do, even if it's something simple like a sinescroller or something difficult like raytracing you will find people here will take the time to explain it all and encourage you.
The goal is to get more and more people releasing things
