David, it's unfortunate that folks have been rude.
Not everyone on WIkiTree agrees that this is a good project, because FindAGrave, like any unsourced user-generated site is not reliable. If there is a photo of a headstone, that at least gives some backup to the info. I have a couple of ancestors who are erroneously connected to parents on FG and when I presented the FG profile manager with the proof and requested an edit, they simply rejected the request. I would be very unhappy if, because of a project like this, someone went in and connected those profiles on WIkiTree after dozens of hours of research on my and others' parts could not come up with a single source to support it and in fact, have evidence to the contrary. I'd likely be unintentionally rude to the user that did that. (But then, I hope we would have entered a research note on the profile describing our research to prevent that in the first place!)
Since one of our goals here is to connect as many folks to the tree as possible, I think we can sometimes be a bit too eager to connect profiles.
The instructions on the project are to use the FG as a hint and search for primary sources. All profiles we put on WikiTree should be sourced. They should have the best sources available. There are research tools "rootsearch" on each profile to help with that. There are usually primary sources to be found. If there are not, then using FindAGrave with an "uncertain " status is something that some of us will do and some of us will not. I'm generally in the "will not" camp because of my experience I recounted above. I would rather put an Unsourced tag "{{Unsourced}}" on a profile, which will tip off others to look for sources, than use FG (or any user-generated unsourced tree) as the sole source. I might put the FG in a research note as a hint for other searchers though.
I think WikiTreers tend to be touchy about unsourced and unreliably sourced claims because many mistakes are made based on people copying unsourced and incorrect information. Unsourced trees (and unsourced connections on FG) are simply family stories until they are proven with sources. They don't become genealogy until they are sourced or at least supported with a bunch of circumstantial evidence in the absence of sources.
Perhaps a good project would be for you to go back to your created profiles and use the RootsSearch tool to find one primary source for each of the profiles you created or tag them as unsourced for other folks who like searching for sources to research, The Help Section has some good info on sources.
I hope this gives you a little insight into why this is a bit of a controversial project.