That is true. The game I worked on was also on PS4 and Xbox One, which are both somewhat similar in architecture to a PC (at least in terms of CPU performance), just slower. If we could make the game perform well on the XB1, we knew it most likely would do well on PS4 and PC as well. But you're right, there could be PC-specific issues that would only show up on low-spec PCs.

In previous console generations things were harder back then as each platform's code was more different than now.