The thought of my entire document in Kate being scanned by an online server to spellcheck it is quite frightening. What else will it do to the document? Check it for WrongThink? What if a word in my document means one thing to me, but means something else to someone in another part of the world? What if a misspelling of a word is actually a word in another language with an entirely different meaning? Will the authorities show up moments later? We all know that ANYTHING we put on the internet is forever.
This is a big reason I don’t advocate the use of online programs like Microsoft Office 365. Even if they work very well, and they do, the lack of privacy is unacceptable.