Ok, let me be more detailed again.
In this thread, which is complaining about people not being respectful, I said that I couldn't successfully run naval campaigns in D&D. Now, no one asked me for any details. I was just told I was wrong and that 5e will do naval campaigns perfectly fine. Ghosts of Saltmarsh was quoted. Let me elucidate in detail why 5e D&D (and 3e as well) doesn't do naval campaigns.
1. Ghosts of Saltmarsh.
Since this was pointed to, let's start here. GoH does have some rules for running ship combat. I'll get to that later. However, it has no guidance whatsoever for actually running a ship. How much are docking fees in Saltmarsh or Seaton? How much does a ton of salt cost and how much markup can I give it? There's a new dwarven silver mine here. They will likely need mining equipment. How much does a ton of mining equipment cost and what is the markup?
Oh, right. I have to make all that up entirely myself, all the while not breaking 5e's laughable economy system in a setting where you can, by the book, buy magic items at any time.
My players took one look at the book keeping required for running a ship, because there are no rules for abstracting it all away, and revolted to the point where the player whose character actually rightfully owned the Sea Maiden, dumped his character immediately and introduced his gnomish artificer.
Yeah, not a success.
Additionally, if you actually LOOK at the adventures in GoS, none of them actually feature anything between two ships. There are no pirate engagements, boarding actions (other than a very simple one in the very first module) or anything like that. Almost all the adventures occur on land - Sinister Secret, Danger at Dunwater, Isle of the Abbey, The Final Enemy, The Styes - six of the seven modules either feature no encounters or at most one encounter on a ship. Not really what I want from a naval campaign. And none of them feature combat between two ships.
2. Personal Experience
I've tried to run naval campaigns in D&D for a LOONG time. I tried in 3e with a homebrew campaign set in Scarred Lands and I ran the Savage Tide Adventure Path up to the seventh (?) module where you defend Farshore. I've run two campaigns in 5e - a homebrew set in Primeval Thule and Ghosts of Saltmarsh. The only reasonably successful one was Savage Tides and, again, like Ghosts of Saltmarsh, it features virtually no actual ship combat. One of the seven modules actually takes place on the ship in Savage Tides and even then, most of the module is about stopping in various locations and exploring. I have very, very extensive experience trying this.
3. DM's Guild and 3rd party Supplements
I own probably about two dozen 3e and 5e ship supplements. None of them actually work. They are either too complicated or too simple. And they all break down in use for one reason or another.
4. Platoon Scale Combat (See, I did get back to it)
The D&D combat ruleset will fight you every single step of the way if you try. The scale is entirely wrong - 5 foot squares? When encounters start at 1/2 a mile away? 6 second rounds? Yeah, that doesn't work. So, you add in 10 minute rounds. Only thing is, the wizard player then very rightly points out that in 10 minutes, he could vaporize that pirate ship before it even got into bow range with his extended range wand of fireballs (3e). Or, well, same in 5e really. The casters just have so many spells that it really doesn't work and it doesn't make sense that every pirate ship has a high level caster on it too. But, hey, we'll ignore that and just make it cinematic right?
So, we get into boarding actions. Your ship has 30 combatants plus the PC's, and the pirate ship has 60. Oh, hang on, each of those combatants take up 5 foot squares and your ship deck isn't anywhere near big enough to hold that many combatants. Where do we put them? Oh well, we'll go theater of the mind and ignore that bit too. So, dividing up the allied combatants, each PC is running his or her own character with sets of actions, and then six or so NPC's, each with their own sets of actions, HP and whatnot. The DM, meanwhile, is trying to track 60 NPC's, each with actions, and, let's be honest, they aren't all the same because some might be standard bandits, while others are scouts, and at least a bandit leader, who has reactions, never minding different AC's, HP's and whatnot.
Yeah, I want to grind through a combat in the next six hours. No thanks.
So, this has been MY experience (I'm not talking about anyone else, just me) trying to do naval campaigns. There are additional issues, but, these four have all been deal breakers. When someone comes up and says, "Hey, I want to do a naval campaign in 5e", then Hell yes, I'm going to tell them it's a really bad idea and to use another system. I'm not doing it because of some white room theory crafting. I'm doing it because I literally have hundreds of play hours banging my head on this issue and failing time and again and I'd like to save someone the pain of trying the same.
Trying to run naval campaigns in 5e D&D will not work. It just won't. Not unless you pretty much sweep under the table virtually every element of actually being on a ship anyway. Why do I say that? Because I've tried it. Repeatedly.
So, just to ask, how is this offensive to anyone?