Isn't that nice . . ? But Heather, we all have bad days. It would be best if we didn't "mouth off" on the internet on those days but there's a risk of it.
I'd like to always be welcoming but often, the first thing a new person has to say is something like, "That looks great." Kind of an attempt to be positive and, of course, not offend anyone. How would I respond to a post like that? Seems like whatever direct response there is to a simple statement like that could be taken as dismissive or sarcastic :/.
Then, you can have someone on the 1st post say something like, "I've searched everywhere on the internet for the answer to this question . . . . . . . " Yikes! That's probably waaay over my head! I am likely to just want to duck and run to cover

. Not very welcoming to do that but
trying to to come up with something but not knowing the answer is just a good way to waste someone's time. Prattling on might just make someone mad!
Then there are the posts that may well just be from spammers. Those posts are too frequent but they really shouldn't stop me from risking a few words to someone who has posted.
Like Marshall, I've signed up for things and promptly forgotten everything I type in on that 1st visit. These days, I've got hardcopies of passwords & such. It was either do that or use the same passwords everywhere. I was told many times that was a bad idea before it occurred to me that these people telling me that, were NOT joking!
I signed up for a couple things and realized that I didn't really need to. "Thinkexist" was one of those. If you search very long on that quotation site, they will asked you to register. So, you register and look at 3 more quotes and you are done . . . Who cares!? I've never signed in again once! If I can't find who-said-what before Thinkexist interrupts my search, I will just jump to another quotation site

.
(Believe it or not, I was just doing something like that trying to remember what it was TS Eliot had to say about garden plants

.)
Steve