Reflections have been around in computer graphics for a long time and they pretty much still work the same way. You create a scene, you have a reflective surface, you calculate vertices from the camera to the corners/boundaries of the reflective surface and then reflect and extend them towards the camera again. The resulting mirrored frame is then being projected onto the reflective surface. This fairly simple concept can be "cake" if you copy the current scene behind the mirror and make it translucient. It can, however, be quite demandung as well, if you have to create the same scene two times only to display the second instance on a reflective surface. Reflection quality is therefore highly selective and adjustable, since higher fidelity comes with higher complexity and cost. Older games sometimes used "pre-rendered" mirrors, that only included the static world, so you couldn't see your avatar in the mirror. Lame. It's not all about mirrors, though. It's every reflective surface. Cars are mostly easy, since their metallic paint is somewhat of a colored mirror and especially sky domes can be easily reflected. The same goes for puddles or wet asphalt. You just sprinkle in some coarse filters for the surface texture and you get a fairly good looking reflection. But the more you think about it, the more complex those reflections can become. And even more so if you factor in Global Illumination and the reflection of light sources.
All of this leads to only one possible step forward: Ray Tracing (with PBR physical based rendering as a bonus). With this step, you can do all 3 (or 4, depending on how you count them) of the beforementioned topics with one solution. Ray-traced shadows, ray-traced reflections and ray-traced Global Illumination, with Ambient Occlusion being the by-product of the latter. Also, screen-space effects are a thing of the past with these, as off-camera scene geometry and surfaces are not excluded from the path tracing. This streamlines and simplifies the artistic efforts in creating scenes. Whether it is important to you or whether you'd even notice the difference att all is besides the point, that Ray Tracing objectively creates more realistically lit and shaded environments. We're just not fully there, yet, since most current Ray Tracing implementations only include a selection of ray-traced effects, e.g. only shadows and reflections or tend to have restrictions in path lengths/bounces or ray count to compensate for calculation time. If you ever laid your hands on a path traced renderer and actually rendered with PB materials and the like, you'll know just how much of a difference this can make and at what cost a single still image can come.