Trying to use a mono output system for stereo signals is a complete waste because you'll lose the nuances that can only be experienced in a stereo system. Therefore, the mono output for video games that simulate real life both visually and audibly ruins the overall video game experience. Yes, stereo is better 100% of the time. Most gaming professionals use stereo audio, rather than mono. The reasoning is that the stereo gives a better sense of direction.
It also gives you a better sense of distance, which improves gameplay. In general, mono or stereo audio is not categorically better than the other. Both types of audio serve a purpose. And both have features that can benefit your listening experience and your recordings if you know how and when to use them.
Stereo is much better for the average listener. It sounds broader, more detailed and more realistic. However, in places that have several speakers, such as clubs, cafes or restaurants, the stereo system can cause phase cancellation problems and therefore make the mono the right choice. Stereo sound is usually better for games such as competitive shooters. In other situations, such as racing simulators, flight simulators or open world games, surround sound could contribute to immersion.
This means that having a stereo audio file has no benefit if it is going to be used in a 3D environment and leaving it in stereo is just a waste of space and resources. In fact, in competitive shooters, the use of surround sound could be a competitive disadvantage, since the game engines in these games are designed for stereo headphones. Known as “pseudo-stereo”, this type uses audio software to duplicate tracks in mono and add effects. As for the professional competitive shooter scene like CSGO, most of them use stereo audio. IMO point source sounds (that is, sounds that come from a specific location that is no wider than the screen) should generally be mono, except for extreme close-ups of full screen, which can be stereo. Unless you're in the competitive gaming scene, stereo audio probably won't make a difference in the way you play.
But there are times when it's better to choose mono over stereo. You can then distribute them throughout the stereo field or the stereo image by moving the audio to the left, right, and center. Recording in mono audio is easier and more affordable because minimal equipment is needed and requires no advanced technical knowledge. This means that many sound effects that you can find on the Internet or in the Unity Asset Store can be packaged in a stereo container even if there is no real stereo content. Mono or monophonic audio describes a mix in which all sounds are mixed together on a single channel.
But keep in mind that the playback will take place in dual mono mode, in which the audio signal is simply duplicated and played simultaneously on the left and right channels. Sometimes, instrumental elements or vocals may sound too distant for your taste in stereo mode, especially if you're using headphones or a multi-speaker setup. However, the stereo may sound louder, since it sends two different channels to the speakers and creates a simulation of space and width. In this scenario, you may want to switch to mono audio to bring all audio layers to the foreground, regardless of which audio channel they play on.