>it's there to prevent entire websites from breaking because some small widget in the bottom right corner breaks, for example.

the issue is that it prevents that, but also allows you to send complete corrupt data forward, that can create horrible cascade of errors down the pipeline - because other components made assumption about correctness of data passed to them.

Such display errors should be caught early in development, should be tested, and should never reach prod, instead of being swept under the rug - for anything else other than prototype.

but i agree - going fully functional with dynamic types beats average JS experience any day. It is just piling up more mud upon giant mudball,