You may not care for it, but this actually touches upon a central issue with stats.
Specifically, dismissing complaints about the stats with the argument "just play the monster smarter".
I can play a goblin smart or stupid, but that's beside the issue. What's in the stat block is what I can see and what I can criticise. Just changing a single number like "Int 11" to "Int 21" makes no difference, or rather, no more difference than changing hp or dex from 11 to 21.
If Strahd only works if run as a slasher antagonist, I require the book to contain specific advice on how to make it so. This might then deflect criticism about any percieved weakness, since it would give advice that makes up for those weaknesses: "Strahd never attacks when all PCs can bring their most potent attacks to bear against him". Perhaps the text tells him to make fly-by attacks through the walls, and discusses how he will react when the players (inevitably) start setting up readied actions. And so on and so on.
Of course, this would then open up the book instead to criticism about the intended genre. Some players might enjoy playing the Castle as a teenage horror show, where PCs wander off on their own, take inexplicable showers or whatever. I'm certain Strahd's stats are sufficient to win against typical slasher victims.
Other groups, of course, would balk at this. They would never split the party. They want to feel like a well-tuned SWAT team that never lets emotions get in the way of optimal damage output. More John Carpenter's Vampires, winching out vampires into the sun to die, than Freddie Kruger. And Strahd doesn't stand a chance against these guys. As others have stated already, he could be dead after his first and only round.
(Myself, I don't want either of these two genres - I'm (much) more of a traditionalist myself. Hammer House all the way. But I digress)
But none of it is actually in the book. That is why it is irrelevant as an argument against the criticism of the stat block.
If the book doesn't say the stat block is not meant to be used against certain ways to play the game, you can't dismiss the criticism from that angle.
What you are saying is really "Strahd's stats are only appropriate for certain ways to run the adventure". Fine, but then THAT should be open for discussion and criticism.