Their audience is Steam users primarily. There are millions of them and all they need to do is market it on Steam. And as Valve had said (and shown with their hardware survey), the vast majority of users have shitty PC's. People keep mentioning in these comments "oh who is this for? I just built a gaming PC with an RX 9070". Good for you. Then you don't need it. However, there are millions of Steam users who do not have a 9070.

Which means what exactly?

Inserting a random factoid does not make a sentence have a point.

Which means that you can "target" all that you want, if you don't have the dozens of millions of USD of advertising budget that your competitors have, you don't really stand a chance against the incumbents.

Steam has a larger user base than the PSN. It is not like Valve is some unknown company unheard of in Gaming circles.

Valve also does not need to advertise to the general public, the general public is not their demographic.