I'm a copy editor. I look at these things in someone's website, because I want to know about them.
These folks are from Chicago -- and yet they use single quotes* in the submissions page, drop final punctuation, and use gratuitous caps. Note that it's once each for these... but since they point out proofreading your final work before submission, O authors, I prefer that the publisher does proofreading as well.
The website is the first contact you have, it's like any first contact. Not looking bad is crucial.
Splatterpunk isn't my style, so I'll be skipping them myself.
The other thing that concerns me, and yet isn't a deal-breaker: They talk about "group of seasoned professionals pulled together from the advertising, publishing, marketing, creative design and social media industries". Maybe their experiences were enough in other fields to make them editors and publishers in dark fantasy and horror.
Anyone who uses gratuitous caps tends to be of a certain age, an amateur, prone to using caps for emphasis... etc. At GMP, they like gratuitous caps. Looks like people who were in PR a long while.
The odds of them being a generation older than me is possible, just not probable.
There you go, enjoy the links. Hope this was helpful to y'all.
* A good marker that yes, one or more of 'em doesn't switch back from social media mode to American punctuation. More people do this today.
And in case you're wondering, the unusual hyphenation continues elsewhere in the GMP site. Everyone's got idiosyncrasies, sure. I do, you do, everyone. Editors should proofread their websites. It is the first example of their work.