17" Dell with a GeForce mobile whatever-it-comes-with will let you play everything fine for 5ish years if you're into the latest shooters, longer for other genres.
Now compare it to the cost of a streaming box & subscription.
I think for most people the decision on PC vs a particular console is:
* Which types of games tend to be available on that platform.
* Which specific games that they like are available on that platform.
* Inertial / brand loyalty based on what gaming machine they had on the past.
* If they play multiplayer, what their friends have.
* How much they like tinkering with / get frustrated fighting against computers.
If you're willing to build your own and buy second hand components on ebay you can just about put together a PC that is competitive with a modern console, at around the same price. But yea, if you're buying new from reputable dealers it's pretty much impossible.
I don't think you are wrong, just more lenient in your definition of affordable. It is compounded by the supply constraints, and markups over retail we are currently seeing. I can buy a 3090 right now on amazon, but it is $2,450, 5x the console price. Titan was ~2x console price.
(Amusingly I'm running the exact card you mentioned, and I did buy it for about $450 NZD used, although the going rate is more like $350 now on the local used market).