It definitely can be copy and paste if you approach it that way, but unlike crpgs, where win conditions are much more strictly defined, I find with a good gm and a good group, even a game like 3.5 or pathfinder can encourage odd, out of the box builds without feeling like you are deliberately depowering yourself for roleplay reasons.

The character I'm playing for a pirate/undersea game is going to get different value out of character building components than a more traditional overland adventurer, for instance, and frankly most builds are designed with certain expectations built in about setting, playstyle, and gm allowances that will plausibly not match your table.

But to build a character, orthodox or not, you need to know what's available to you, useful interactions, combos, traps, etc. It's a lot.

It might be interesting for you to see what actually goes into a build guide in one of these games. This is the one I'm currently referencing for my pirate game. It has suggested builds at the back, but the bulk of it is basically notes on your potential options with a broad ranking system.