It's more advanced than just syntax. It should be able to understand the double meanings behind riddles. Or at the very least, that books don't have scales, even if it doesn't understand that the scales that a piano has aren't the same as the ones a fish has.
It's a sourcebook they charged money for. They couldn't have bothered to do basic playtesting to earn that money?
And there's plenty more where that came from. Between a Shadow and a Tarrasque, one can safely be beaten by a low-level party, and the other is a threat to the whole world. The CRs reflect that, except they're backwards.
In fairness, caught early, Shadows wouldn't need a level 20 party to stop them. But they're still above CR. And with the Tarrasque, all they had to do was leave in the anti-cheese measures they already had. And steal all the immunities from Pathfinder.
Speaking of CR, that was a bad way of doing things. Sure it's convenient if you have a party of four players fighting a monster, but if you have to figure out how to recalculate it based on different party sizes, you may as well just use level to begin with and then figure out what level would challenge your players. Then it would work just as well on enemies with class levels. And it would mean Polymorph could be at least somewhat close to being balanced. As it is, a single spell can turn one party member into a monster capable of challenging for characters of that level, and then when defeated, they still just turn back.
It's impossible to make it perfect, but it's trivial to make it better. For example, get rid of Silvery Barbs.
And we'd really hope with a large corporation behind it, they could do more than get rid of the obvious. They could do the playtesting necessary to properly balance martials vs casters.
But it is useful for someone to make rules that are balanced and lead to interesting gameplay. There are entire companies that make their business around printing rule books and selling them to people who think it's worth the money.
Think of it like this: if you have a high enough GM skill, then you'll pass whatever check God has and make the game fun. But with more balanced and interesting rules, you get a bonus. Even if it's just a +1 bonus that makes your game 5% more likely to be fun, that means everyone who plays that system gets that bonus from one person making it. You'd be crazy not to do it.
Different things work for different groups. But some things tend to work well in general, and others do not.
I admit I've only played D&D once. We spent half an hour working out how to go through a hole in the ceiling when there was an unlocked door in front of us. I thought that was just part of the fun.
I think the problem is that it's something not actually bad. Making a BBEG that's just a punching bag for your believe that murder is wrong is perfectly okay.
Honestly, RAW just doesn't work. If you can't do anything unless specifically allowed, then you can't do anything because whatever you do will always be more specific than what the rules say. If you can't do anything unless forbidden, then it doesn't work because there's so much the rules didn't bother with, just leaving it to common sense. And then there's the fact that sometimes rules contradict. Sure there's a rule that the more specific rule overrides the general rule, but that's just yet another contradicting rule on the pile.
There's nothing specifically saying whether or not you can move left. There's nothing specifically saying whether or not you can move through walls. We all know you can do one of those but not the other, but it's not because of anything the book says.
Granted, the book sometimes gives creatures special abilities that let them move through walls, which would be an odd thing to do if it's something you can do anyway, but the game constantly goes into different levels of detail about things.
Why would it matter if it says you die? It's not like there's a rule that dead characters can't take actions. Or that they transform into objects. Or get sent to another plane of existence depending on who they worship and their alignment while leaving an object behind.
You could say that about anything. You want to move left? Point to where it says, RAW, that you can move left.
You can do anything unless the rules forbid it. And there's nothing forbidding continuing to play after your character is transformed any more than there is anything forbidding you to play while they're wearing a red shirt.
Two-handed weapons require two hands, and one-handed weapons require a free hand to load. But you could use a one-handed weapon that you don't have to load. Or rather, you don't even need to do that, since no weapons are listed as being one-handed.
Why does it have scales but no wings? Also, lots of living dragons don't have flame and breathe lightning, acid, poison, or cold instead.