In reply to Felix.

>> 2. WordPress is *fragile*. <<

I don't know of many products and services that can handle such a wide range of 3rd party products as well as WordPress. (Can you imagine looking askance at Mercedes when car owners add on products not produced by Mercedes that then break the car?)

When even one bad line of code can mean the difference in almost any application, I don't find it surprising at all that a plugin (that has to be rolled out to so many different hosting environments and setups; and created by such a diverse set of developers) could create a serious problem.

That's why a testing environment is considered best practice and why, when amateurs ignore that, developers have to remind them. (Or get paid the big bucks to help them clean up their mess! Kudos to you for your work; I hope they know to appreciate you!)