system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why aren't all the ships (human, borg, Klinger, etc.) and other technologies (weapons, transport vehicles, etc.) all borrowing the best features from all the different species, why must each species stick to their own design no matter how inefficient?
gpt
How do you define "Best"? Depending on the capabilities of certain species, their ethics, available resources, and other factors, they may see no reason to borrow tech from other species.

That being said, that is basically the explicitly stated purpose of the Borg already, though what the consider worth assimilating is not always clear. And the Klingons once allied with the Romulans re: ship design and cloaking tech, so its not as if each faction is trying to isolate its own technological progression. The Pakleds and Ferengi also seem to use this as a strategy, the former constantly looking for things "that make them go" and the latter basically having bought their way into interstellar technology. The Federation seems to be given the most context here with multiple technologies and weapons systems considered either too dangerous or unethical to be used or owned by its citizens (or in the specific case of cloaking, banned by Treaty).