Absolutely! There's been speculation that Marvel authored some of those letters. And I have read that Flo Steinberg and others on staff would do some rewriting "for clarity" but really, it seems it was done to elevate the caliber of the letters. It also explains, to me at least, why the letters sound similar in tone (note: as always I am referring to the mid-late Silver Age, which is when I was reading comics.)

For me as a young fan back then (in grade school), I was totally intimidated by those Marvel letters. So I reserved my letter writing to DC, I never dared to write to Marvel. My DC letters were of the kind you describe--very childish, as befitted my age!

The letter columns of those times are a topic I'm fascinated by. The nitpicking you (correctly) mention seems to me to be found mostly in the Superman books, which from what I understand were deliberately aimed at kids and young teens. But now, as an adult who's been reading some of the Silver Age DC lettercols for the first time, I've come across letter columns that contain letters from older fans, such as in the Schwartz-edited books. I am impressed by the letters written to books like Flash and Atom. A lot of letters about scientific matters (which go over my head, lol). Very impressive! Plus Atom's letters also focus on Gil Kane's art; I am amazed at how savvy these readers were regarding art techniques and artist recognition. They could spot a different inker in a single panel a mile away!  There were also a lot of letters about art in Hawkman's book, specifically about the wonders of Murphy Anderson. Again, very literate letters.  

What I was going to say.

Thanks! *smiles in reader of the old issues*

No, the letters pages in DC basically reflected the age of their usual readers. Marvel followed the example set by Schwartz and exploited their popularity with older readers, especially highlighting letters from college students.

What made the Weisinger letters pages off-putting was not the less erudite letters of the readers, but Weisinger's bullying responses. He was needlessly dismissive and sometimes nasty to his readers. As a reader, you sensed that he had no respect for what he did. he couldn't even fake it.

Check out Murray Boltinoff's letters pages in Doom Patrol, Challengers, and Tomahawk as examples of how to welcome readers and create a sense of camaraderie between them and the creators, sans the incessant self-adulation of Smilin' Stan. 

Later on, Dick Giordano established a similar rapport in his DC books.

Editorial in comments 60s Marvel lettercols were 50% "Thank you, we know are the most awesome thing ever" and 50% "We have no idea what we are doing. It is a miracle you are even reading these words."

Well, of course, a brief statement like mine can't possibly cover every book/era. And I can only judge the books I picked up.

It's like anything. If drivers in orange cars kept cutting me up in traffic, I'm gonna have a bias against drivers of orange cars - even though the reality is there'd be hundreds of drivers of orange cars that are perfectly safe and reasonable.

Purchases of Silver Age books by myself has been haphazard, random and non-chronological.

I really picked up my purchases of US comics in the early-to-mid 90s (it was more UK reprints in the 80s). I picked up a lot of Supes' titles. They had letters pages comparable with anything from Silver Age Marvel, with thoughtful letters about Clark's life, Lex Luthor, the Clark/Lois dynamic, etc.

In a way, it's sad that the "laundry list" letters became extinct. At least with those letters, you knew a younger audience were writing in. It's been a while since I've seen a "laundry list" letter in a comic.