In other words: blocking random scripts might cause sites to stop working. Who would have thought? This is the equivalent of deleting a random third party analytics library and complaining that your app no longer builds. Sure, there's the concept of progressive enhancement or whatever, but at the same time it's also unreasonable to expect the developer to accommodate the possibility of any third party script getting…
> possibility of any third party script getting blocked I'd say it's not unreasonable. You're giving your third parties the ability to break your business. Third party scripts are blocked or just fail to load all the time, APIs change suddenly, etc.
What's your strategy for dealing with jquery not getting loaded?
>APIs change suddenly, etc.
That's going to be an issue regardless of you check whether the script is loaded or not.