Agree.
Oh absolutely agreed. There are a lot of different styles of games and different tables will enjoy certain things and also will different players will have (fairly or unfairly) some hard "no" where they draw the line on what they can enjoy. And while you can run pretty much any style of game with any game system, some systems will fight you more than others depending on what you trying to do.
Absolutely agree. A dungeon is so much easier to prep than event based and character driven play and more importantly, so much easier to do adequately well and hit everyone's aesthetics of play. You can always with a little thought put social encounters in a dungeon, and eventually you start realizing that everything is a dungeon and from there you can start working with bigger stages without ending up with something degenerate or trivial.
In general, I agree with Ginny that "don't overprep" is terrible advice for a newbie DM. IME, the single biggest indicator of how good a GM is is how much time they spend prepping. The truth is, if you had limitless time, there would be no such thing as over prepping. The more detail to prep for, the richer and more immersive the game can be and the better able you are to handle and provide for player agency while still bringing the twists and narrative arcs that give your game big payoffs.
"Don't overprep" is actually, if we are to be generous with it, shorthand for some much more complex advice that a novice DM is not going to understand without a whole lot more explanation. It's a recognition that we as GMs don't have unlimited time and so we have to choose what to prepare. It's also a recognition that it's possible to prepare badly, leading to the GM either thinking about their game in the wrong way (budding novelist) or being actually completely unprepared for what happens in play.
It means things like, "Don't prep the wrong things. Focus your prep time on the things that are definitely going to come up, and not on the things that aren't. Or to put it in a phase, don't world build to the exclusion of having a rich neighborhood to explore."
It means things like, "Don't prep out a lengthy storyline in detail, because you never know exactly what is going to happen. And don't spend a lot of time fantasizing about the exact events that you want to have happen and how cool they will be, because not only will it turn out much of your prep is made obsolete by player choices, but you'll be tempted to railroad players or disappointed your plans don't come to fruition."
It means things like, "Don't prep for things you don't yet know if you have player buy in for. Make sure you know where the players want to go and do before you plot out the whole railroad or build out the whole sandbox. If you aren't sure, ask them in session zero or at the end of a session."
As far as the "Lazy DM" goes, whether or not the Lazy DM is giving good advice or not depends very heavily on you and your players tolerance for illusionism. I personally have a really sensitive illusionism detector and I personally hate, loathe, and utterly cannot stand illusionism. (By "illusionism" I mean that the game universe shapes and reshapes itself according to the metagame. Nothing is actually fixed until a metagame need establishes what happens. Simple illusionism and somewhat forgivable illusionism might be an event that is timed to occur when the PC's arrive at a location, and not at a fixed time in the game universe. That is to say a can't miss event. The Lazy GM veers toward advising the GM to save prep time by doing everything in response to the metagame.) If my illusionism detector pings off, I probably won't get up from the table and walk, but I probably will politely decline to ever play with you again and speak poorly of your game and even be a little bit angry. You try to pull the "Lazy DM" BS with me, and I will not only notice but will pack my bags. I'm not kidding. I left a group after 5 years in large part because a DM pulled a Lazy DM stunt on me. Probably not fair and yes it's probably an exaggerated pet peeve, and yes I know as a DM everyone uses a little bit of illusionism from time to time for reasons good and bad, but still it's a thing. The trouble with illusionism is it works really well as long as players never know it happened, but as soon as they find out that it happens you've got a problem.