That's a bit of a contradiction, though.
Elden Ring sold a lot more copies than Dark Souls precisely BECAUSE it tried (and succeeded) to get a new audience.
What you're talking about is a success story where the changes they made happened to hit a sweet spot. That doesn't mean they didn't make changes. Elden Ring is not just a Dark Souls reskin. It just means they made GOOD changes, or at the very least, they made changes conducive to attracting a bigger audience.
And that's a fair, if a tad trivial argument to make: if you change something, do it well.
What it's not is somehow a support for "don't try to get new audiences" when the entire POINT of that project was to get a new audiences interested in DS-like games.