History lesson: no, WWI veterans didn't get the attention they needed. This is wistful conservatism wrapped in a shroud of comedy. Don't mistake it for truth or wisdom. The treatment of Vietnam veterans was not a departure from the standard practice of wars predating it. The depth of their trauma was a departure, and that was the eye-opener that primed us to take PTSD seriously in the aftermath of the wars of the 21st century.
Now, PTSD (a four-syllable, jargon-free, hyphen-free term, if we're counting) has received greater attention than it did in the previous century of wars. It's recognized to effect more than just soldiers (which "shell shock" doesn't really cover), and progress is being made on a variety of treatments. George Carlin is funny, but that doesn't make him right.