Title? I don't need no stinkin' title.
You do you. I've given my opinion, which is all it is at the end of the day. You don't get to tell me my opinion is wrong.There's no logic there, just assertion. You never say why it's flexible, or what flexible means, to you. That's the ask.
So, to you, flexibility is setting options? The difference between playing Eberron and Barovia? That's at least an answer, so thanks. However, if flexible is just setting, how is 5e more flexible than any other edition of D&D? The can ALL do this.
Here's where we're going to disagree. The stylistic change is very slight, given the range of actual possibility across all RPGs. Again, we've had some long arguments and intractable differences about how the game works, but your players would be just fine at my table and my players at yours. This is pretty much true of D&D in general. It's only if you're making extensive changes to the rules, or ignoring them, that differences occur, but that's not a feature of 5e, it's a feature of people.
No, I don't say there's no flexibility, I'm saying it's not actually all that flexible.
Nothing you've provided wasn't possible in older editions, though. I'm not seeing the specialness. Critical Role started with Pathfinder, which is essentially 3.x.
Yup, if you're making up the rules, there's not much system there to flex. This is, again, not a feature of the system, but a feature of people.