The core metric for TypeScript's success was to be able to put an IDE in a browser able to run and compile TypeScript itself, which is what the TypeScript team did with the Monaco (and Visual Studio Code) editor in 2011.
Monaco is just the GUI, it doesn't require language support (and in fact, the LSP that was pioneered alongside it means you don't even have to run the language support on the same machine, much less in the same codebase)
Again- any references for this claim? Genuinely curious if this is part of TypeScript's known history, or if it's just speculation
