So, in this you elide from "we" to "one".
Let me counter that with... novels. One person can only read so many novels in their lifetime. If one person can only read X novels... do we not only need X novels to exist, ever? Of course not., because we have millions of different readers, with different desires. We need many times X novels to exist, so that folks can have choice.
We have millions of people who play RPGs, too, so, we can reasonably have many times the number of games any one of us can hope to play to allow for choice and personal preference.
What "one" needs, and what "we" need, are not the same.