Here are some thoughts about the thread topic:
(1) Some RPGs use random PC generation; those RPGs don't really have optimisation in any meaningful sense. Maybe they allow gambling (eg in Classic Traveller you can keep trying for further terms of service, which can allow more skills and starting gear for your PC, but risk (i) stat loss due to aging, and (ii) PC death and having to start over due to a failed survival role), but gambling isn't optimisation.
(2) Some RPGs have very transparent PC build. For instance, in RuneQuest the way you get good at doing X is by having a high skill in X. PCs in these games can be more or less powerful, but there's not really optimisation.
(3) Building a PC to be able to do the things you (as a player) want to be able to do in the game isn't optimisation. Choosing to build a fighter in a D&D game, rather than a wizard, because you want to play a character whose good in hand-to-hand combat isn't optimisation. Some games have broken choices in this respect - eg there are non-obvious builds that end up being better at X-ing than the obvious ones - but that's a problem with broken build rules, not optimisation.
(4) Optimisation is about adjusting parameters so as to enhance performance. In RPG PC building, that means adjusting build components to achieve enhancement, normally via synergy/interaction between particular build components. This depends on the build rules having parameters that can be adjusted: 3E and subsequent versions of D&D exemplify this; so do points-buy games. There also needs to be a measure of performance that it makes sense to try and enhance.
(5) Once we're talking about enhancing measurable performance we're getting pretty close to a win condition for the game. So a RPG that has complex PC build rules with multiple interacting elements, and that has a win condition or something in that neighbourhood, is likely to foster optimisation in PC build. Conversely, a RPG that has simple and/or transparent PC build rules and that doesn't have a win condition is likely not to feature much optimisation in PC build.
(1) Some RPGs use random PC generation; those RPGs don't really have optimisation in any meaningful sense. Maybe they allow gambling (eg in Classic Traveller you can keep trying for further terms of service, which can allow more skills and starting gear for your PC, but risk (i) stat loss due to aging, and (ii) PC death and having to start over due to a failed survival role), but gambling isn't optimisation.
(2) Some RPGs have very transparent PC build. For instance, in RuneQuest the way you get good at doing X is by having a high skill in X. PCs in these games can be more or less powerful, but there's not really optimisation.
(3) Building a PC to be able to do the things you (as a player) want to be able to do in the game isn't optimisation. Choosing to build a fighter in a D&D game, rather than a wizard, because you want to play a character whose good in hand-to-hand combat isn't optimisation. Some games have broken choices in this respect - eg there are non-obvious builds that end up being better at X-ing than the obvious ones - but that's a problem with broken build rules, not optimisation.
(4) Optimisation is about adjusting parameters so as to enhance performance. In RPG PC building, that means adjusting build components to achieve enhancement, normally via synergy/interaction between particular build components. This depends on the build rules having parameters that can be adjusted: 3E and subsequent versions of D&D exemplify this; so do points-buy games. There also needs to be a measure of performance that it makes sense to try and enhance.
(5) Once we're talking about enhancing measurable performance we're getting pretty close to a win condition for the game. So a RPG that has complex PC build rules with multiple interacting elements, and that has a win condition or something in that neighbourhood, is likely to foster optimisation in PC build. Conversely, a RPG that has simple and/or transparent PC build rules and that doesn't have a win condition is likely not to feature much optimisation in PC build.