Have you noticed that commas can be difficult? A tendency to overuse them is a very common affliction.
For example: "This message is intended as a tongue-in-cheek comment for the vast majority of
you, who are good and friendly folks."
What is the purpose of the comma above? Totally unnecessary.
And then this: "Have any of you ever posted a thread/made an inquiry you thought was
important, only to see it get derailed in 2 seconds?
What is the reason for this comma? None.
And then this: "If you can't resist the urge to hijack a
thread, just come here and vomit out your unnecessary verbiage!"
Also no need for the comma above.
But here we have a run-on: "Welcome
aboard, start building those verbal sandcastles you enjoy foisting on others!!!
This is known as a comma splice. You have put together two sentences with just a comma in between. You have several choices to fix it. You could use a period or a semicolon. You could even use a comma with a conjunction like "and". But the comma by itself is incorrect.
I'd like to sarcastically suggest that if you can't master middle school grammar, you shouldn't post more than one sentence at a time!
There. Did I hijack properly?