jointhefediverse.net seems to be a commonly linked resource for directing people to join the Fediverse.
Curiously, it does not list Lemmy under the list of Reddit alternatives. Their GitHub README explains why.
Previous relevant discussion: https://lemmy.ml/post/78808
Because as the leading “Fediverse alternative” website, it essentially tells the viewer that Lemmy doesn’t exist, which I think does a disservice to prospective Fediverse users.
But yes good point, anyone can make an alternative website, I think right wing people made like a fuckgab.com site back in the day to recommend Gab alternatives on the Fediverse.