I think the Godzilla scene is older and has a more dedicated fanbase, but with fewer people outside it with any real awareness of the franchise beyond "big rubber lizard".
I think most people have seen and even enjoyed an Alien movie, and quite likely seen and not enjoyed more, but being extremely casual viewers have no reason to engage with fandom communities.
And for the record, I also think websites like this and podcasts have mostly replaced magazines for niche interests, Godzilla having an older fanbase and still publishing a magazine is something I do not think is a coincidence.