It's still more nuanced than that. As I've mentioned in my post, Microsoft have been pushing hard the PC side of Xbox. So it's really more Playstation, Xbox and/or PC. Then if you introduce the PC you have Steam and all the other stores too.
Also don't write the Switch off for serious gamers either. Most gamers I know who have an Xbox or PS also have a Switch. Why is this important? Because if someone has £50 to spend on a game, they cannot spend that same £50 on both the PS/Xbox and the Switch stores. So even if the Switch occupies a slightly different market, it's still taking money that might have gone to Sony or Microsoft.
Also don't write the Switch off for serious gamers either. Most gamers I know who have an Xbox or PS also have a Switch. Why is this important? Because if someone has £50 to spend on a game, they cannot spend that same £50 on both the PS/Xbox and the Switch stores. So even if the Switch occupies a slightly different market, it's still taking money that might have gone to Sony or Microsoft.