you can't do what a Series S does for $250 with a $250 PC. Plus with gamepass the math doesn't even need a napkin. It's simply the best deal in gaming right now, whether you're paying for online play or not.

The consoles themselves are often sold at a loss because they know they will make that money back on games. Which is a better value proposition is arguable, especially once you factor in how much more you'll be paying per game relative to steam sales, the ability of PCs to do things other than gaming, and the inevitable obsolescence of consoles. I can still play games on a modern PC from when steam was new.
Microsoft also offers a game pass for PC, but I'd rather own my games.