I'm sorry but I strongly disagree. If the GM can't tell you what the campaign is about, if it's just combat and big dungeons all over it or if you can expect investigation, roleplay and other things, there's a big issue. All the GMs I know answer this kind of questions as everyone needs the answers to make a character who fits in. Bringing a Barbarian in a campaign which is all about stealth and urban investigation will be as disappointing as bringing an Alchemist in a dungeon-heavy campaign.
There's a difference between what the campaign is about from a broad sense and the specifics. Its the difference between the setting and the plot. I'll point to abomination vaults and extinction curse here, abomination vaults is very clear its a big long dungeon crawl. Extinction curse follows a travelling circus, but the first book has 2 dungeons and several days worth of high encounter days. I'm not willing to say either is "bad" either, if you spell everything out at the start there's little to surprise the players with, they're different approaches. The types of encounters and enemies you face, as well as the length of adventuring days and number of rests are often not directly connected to the setting of the campaign, but the details of the plot instead. Two people could both write a campaign about crime fighting in a dirty city, and one could have mostly short, one encounter per day adventures, while the other could have long adventuring days trekking through criminal hideouts and being chased and tracked. Neither would need to have more or less intrigue/politics/roleplay than the other either.
There's also more sandboxy homebrew campaigns (which I love the most but haven't done in a while), where the DM isn't really writing more than a session ahead outside of broad plotlines. Generally you start with a setting, and give the players a reason to be together, then feed them plot hooks until they bite and you roll with it.