You don't get to decide what I find silly Acererak...
You don't find Spelljammer silly? You don't think that Modrons are silly? Or skunk-throwing kobolds? Or zombie T-Rexes that vomit other zombies? Or floating alien jellyfish with telepathy that shoot stink spray at people? Or Flail Snails? Gnomes? Or
Sea Lions that are actually lions with fish tails? Seriously? You don't think that literally any of that is silly, but somehow think that having a Rio-style Mardi Gras in a D&D book is so childish that it makes you want to mock people that like this version of D&D and boast about how you're playing "adult" D&D from decades ago?
Yeah, you're either acting in bad faith or have your head on backwards.
And I don't have to buy the books to get a sense of their tone. Plenty of previews online, not to mention I can walk into my local store and flip through it.
Yeah . . . yeah, you really do. Or, at least, to get a fully accurate sense of their tone you need to. "I don't have to even read the book to know that I don't like it!" is not a compelling argument. There is plenty of serious D&D that's been released in the past 4 years (Avernus, Ravenloft, Fizban's, Netherdeep, Theros) and plenty of wacky D&D that was released before then.
You'd never realize that child slavery is a part of Witchlight, learn about the fairy suicide in Candlekeep, or know about the true story behind Netherdeep just by skimming through the books or looking at their art online. In order to truly get a sense of what the book is like, you really do have to read the thing.
We can have different opinions. It's okay.
Ah, the "It's okay if I'm objectively incorrect, it's just my opinion!" defense.
You've admitted to not reading the full books, have tried to say that there was no goofiness in early D&D (proven false by the mere existence of Spelljammer, Flumphs, and Owlbears back to the TSR era of the game), and cherrypicked art from a couple of recent D&D books to support your argument when there are literally dozens of pieces of art that directly contrast the overall point that you've tried to make and
have continued to ignore. D&D 5e can be (and often is) serious, gritty, and dark. It still is, even in these last few years that you seem to think are nothing but bubbles, sunshine, and fairies for some reason. The people that have actually read the books and have run games with them are the ones that actually know what they're talking about. You don't.
Having an opinion is not a suitable replacement for factuality. Having an opinion does not make your opinion as valid as those more experienced/knowledgeable in the subject matter.