Can't agree with you more. I don't personally think the label means much more than a ballpark for the grade I'm looking for (given the variation in grading). But you're correct about the preservation problems with the CGC holder, something that nobody seems to want to talk about. Comics date back before the 1940's. That's 70+ years of preservation, of which only the last 10 or so has the CGC been a part of our hobby. I don't personally own an Action 1 or even Amazing Fantasy 15 in high grade but if I did, and I wanted to keep it in good condition for the next 30 years of living with me, I wouldn't keep it in a CGC Slab. SCS or otherwise.
The label is good for a ballpark estimation of grade. That's it. And chasing "highest graded" books is a fool's errand, short term and long term.