I could explain it as Dart not having any features other than what any of the mainstream language has but that would not be much of an explanation would it? What is special about Dart?
I'm aware we have plenty of mediocre mainstream languages existing right now, but they all exist for historical reason and have rather useful ecosystems. However, to go out of the way to just make a new lame ass syntax, with zero ecosystem, and no distinguishable characteristic (which is why Flutter is always involved in selling it) why would you do that?
I'm all for new new paradigms, languages that are different like haskell or scala to flourish and teach us new ways of thinking, this is not it.
When Dart was launched Javascript (Typescript) was not really a enjoyable language to use. For me at least it filled that void as a strongly typed language I could use on the web and server side that was easy to pick up. I thjnk that was the niche it was trying to fill and wasnt just made for the sake of it.
The original mission of replacing JS in the browser failed. At that point they could've called it off. Instead they doubled down with Dart 2.0, which, could've been great if there is actually anything 2.0 about it. It's still just some language with curly braces.
During the same time frame of Dart's existence, other languages that actually have innovative ideas were able to carve out their niches (go, rust, ts, kotlin, swift... list goes on), while Dart still has to rely on some UI toolkit to sell.
I'm aware we have plenty of mediocre mainstream languages existing right now, but they all exist for historical reason and have rather useful ecosystems. However, to go out of the way to just make a new lame ass syntax, with zero ecosystem, and no distinguishable characteristic (which is why Flutter is always involved in selling it) why would you do that?
I'm all for new new paradigms, languages that are different like haskell or scala to flourish and teach us new ways of thinking, this is not it.