I did something I really didn't want to do. I read through all of PhoneLobster's posts again on the subject. I'm pretty sure it boils down to he and I disagree on what counts as 'gated content'.
I'm going to use his Camelot example. For the rest of this example Camelot is a floating cloud castle populated by chivalrous giants who go on quests.
If the party
wants to go to Camelot, there are lots of
valid reasons why they cannot. It is
entirely appropriate for Camelot to be 'locked content' that they can't access easily or immediately. If the party is 3rd level, lacking access to flight makes Camelot generally inaccessible. But just as 'open locks' can make some content areas accessible, there are other skills that can 'unlock' Camelot. Having Wild Empathy means you can, through the use of a skill check, convince a Hippogriff herd to carry you to the castle. That successful skill 'unlocks' additional content.
If the content doesn't go away, the party would be able to access it later (say, when they are high enough level to fly reliably). Accessing the content
early is a good use of a skill. The party gets a benefit from having invested in a particular skill in that they're able to access content that they otherwise might not be able to. If the party
chooses not to invest in that skill, they will not be able to access the content early - at least in that manner. There may be
other ways to access that content, but until they find such a way,
that content is locked.
Now, I will agree that there are adventures that have important content that is accessible in only a single way, and failing to access it is usually a bad thing. That's the result of bad implementation, not necessarily an indication that gating is bad.
In nearly every conceivable scenario there are options that are on the table and options that are no longer available because of the PCs choices up to that point. A bunch of 'lawful-goody-two-shoes' probably aren't going to be able to pretend they're willing to switch sides to gain an advantage - but a 'morally-ambiguous' group might have that available as a potential gambit. Locking out the 'pretend to be bad guys' content doesn't cause the game to end. It means that the players have to select from a different menu of options.
Other skill checks should (and other content unlocking abilities) should work in generally the same way. Choosing a particular option should never lead to 'game over', which is a ridiculous shorthand for 'any bad thing, ever' or, to quote you exactly:
PhoneLobster wrote:
"GAME OVER!" has always been about simply being the clearest and simplest example of "BAD OUTCOME/CUT CONTENT".
Trying something and it not working is usually 'worse' than trying something and it succeeding, but both can make the game more interesting. Always succeeding on the first try is not terribly interesting. If your 'shortcut' or 'knot cutting' ability doesn't succeed, then you get to do things the more difficult way. And just because the 'more difficult way' can be fun, doesn't mean that you want to use it
all the time. It's good when sometimes players succeed and either get content they normally wouldn't or early access to content.
If I allow a skill check for the PCs to gain flying mounts I'm indicating that I'm
open to them accessing content that wouldn't normally be available. There's still lots of ways I can make this bad. If the DC is always 1 higher than they rolled, then I'm not actually allowing content to be opened and I'm a bad person.
But gated content is not a bad thing. It is almost certainly a good thing. Your point that SOME CONTENT is locked UNNECESSARILY and makes the game LESS FUN is valid, but you've approached it in the most hyperbolic and ridiculous manner that your intended point was lost.