I’m not really involved in javascript land so im parroting off of what i’ve heard for “why js over ts?”

• it reduces file size since you no longer need to ship source maps
• ctrl+clicking stuff will take you to the definition rather than an unhelpful type declaration
• if you spot a bug in the library, you can edit the source directly than having to recompile/reimport
• ts adds some unnecessary type “gymnastics” (can’t speak for what this means), when all they really want is intellisense thru jsdoc

So mainly: devs who don’t prefer strongly typed languages, and library devs who find typescript to be less transparent and more time consuming for new and old contributors than it’s worth