B4: The Lost City is a classic module for D&D. At one point it (in)famously stops giving full description of the rooms but instead lists monsters in each area and tells the DM to figure out why they're here themselves. Once the reprint will show up in new anthology, I'm sure people who complain online whenever WotC uses "ruling not rules" or "DM decides" or "these parts were left for the DM to fill in" in their design (and then continues buying WotC books to keep bitching and doesn't touch 3rd party or other games for some reason) is going to be normal about it. /s
Oh I'm not. I don't even play 5e anymore unless someone else is running it. I moved my setting and campaigns to Savage Worlds.
I did so because I don't like that WotC sells me books that are half baked and claims it's up to GM to write the content they paid for.
Also the entire debacle the other year with the OGL.
I don't buy WotC after OGL, but I do not think it's necessairly bad to leave some things up for DM's decision. maybe not sailing rules, but still
There is leaving space for the DM to inject some creativity, and then there's deciding that you don't need to actually produce a complete product because you know your customers will do it for you anyway.
I mean, it's not like any of the published rules are mandatory. Just because they're in a book doesn't mean you need to use them. But them being in the book means you don't need to come up with your own half-baked, undocumented, and inconsistent "rulings" if you don't want to.
And, frankly, it's not a symmetric situation. Published materials are suggestions that, ideally, are crafted by experts and well play-tested that may be ignored if chosen. Unpublished materials cannot be opted into.
Also if its from the developers of the system you also, hopefully, can assume that they are keeping with their own visions and intentions which should be healthy for the system. Even if its just "Story" content, it'd be really weird to see a room full of random sci-fi crap in what has up until that point been mostly a gritty fantasy dungeon. Also, people can rail against this all they want, but people tend towards authority. The developers and publishers saying X feat or edge or whatever is useable in X setting, it doesn't leave a lot of room for inter-group bickering about it, but even then its opt-in.