Very much this. It's obvious the MM design was intentional, and based on information as to what bests fits the design scope of 5e, and what most people wanted. Heck, Mearls has said more than once about how the design of 5e is heavily influenced by playtest feedback even to the point of them omitting some things Mearls personally liked.
So if I could have my magic wish, it would be that people would stop with this argument that the design team is incompetent in some way (dropped the ball, didn't think of this, put not effort, etc) and that you are being punished (suffer the consequences) by the current game. It simply is not true, and the design team certainly doesn't deserve to be constantly insulted. They knew what they were doing, and had a clear goal in mind. Looking at the success of 5e, they made the right decision. Does it make everyone happy? No, but "not exactly to my preferences" does not mean they screwed up, and frankly needs to stop being the go-to excuse.
I am positive the success of 5th edition is completely independent on the stat block of a few high level critters, none of which will feature in a new campaign for many, MANY sessions.
I am not contesting the MM design was not intentional.
I am postulating they took it one step too far. Quick simple orcs and ogres? Great!
Equally simple "captains at the head of a demonic horde" with "keen minds and a finely honed
sense of tactics"? Sorry but "simple" now turns into "simplistic".
An Ogre does not need a way to overcome the many and varied ways a high level party can prevent you from charging into battle to shish kebab you with six blades, because it is not meant as a credible high level foe.
A marilith however, needs to if it is to be able to challenge veteran players. But the only tools that separate it from the Ogre are:
- it can gain AC 23 against one attack per enemy
- it can teleport
- it can grapple at the same time as it attacks with weapons
To me, that's a demonic grunt, not a demonic captain. Contrast the d20 Marilith, that mirrors a high-level fighter in that it gets what we now would call extra attack, it sees through illusions and invisibility, it can even throw up a blade barrier for some battlefield control of its own.
The teleport is nice - at least it isn't once per day. But the problem is that it takes the Marilith's entire action. A party will not be able to keep away from the "demonic captain", but they have ample opportunities to deny it any attacks. Just giving it the fighter's action surge would considerably up its threat level, because then it can at least once both teleport into range AND unleash its full barrage of attacks.
None of this means I'm advocating a return to 3E - there are a lot of fiddly details in the d20 stat block that none of us wants to see come back.
Fixing this would NOT have impacted 5E's success. There is NO grounds for making broad sweeping claiming this is "what most people wanted" or relativize things with rhetorical and dismissive questions like the old chestnut can everyone be happy - that just makes it look like you want to sweep fair criticism under the rug.