I can't see that being the case
There are many collectors who know how to grade and don't need CGC to confirm what they already know. The restoration check is helpful, but that aside, the experienced comic collector can trust their own judgement on structural condition and grade if they choose.
But not everyone has those skills. Those new to the hobby, or buying for investment purposes may not know the difference between a well centred 9.4 and, say, a mis-wrapped 9.4. My ASM 129 has a significant mis-wrap. It's a 9.4 and I got it fairly cheaply, possibly because of the mis-wrap. If an investor dipped in, and saw two 9.4's, one with a CVA Exceptional sticker and one without, which would they prefer do you think? CVA gives them a hint.
If there were two similar looking Action Comics #1's out there, one an 8.0 with a CVA and one without, which would you prefer to own? If the answer is the CVA copy, then it follows that you might just pay a bit more for it, if you were in that purchasing field.
So CGC and CVA are not nonsense. They are a service with potential benefits to some. Use them. Don't use them. CVA stickers on the OP's books may pay for themselves and some, if the intent is to maximise resale value. But if there is no evidence of that being the case however, which sounds counter intuitive to me, then at least you'll have the pleasure of knowing you have a third party's confirmation that your book is a looker.