It doesn't sound like you understand what personal information is. It includes things like contacts, calendar, and emails.
This back end service exists because, in the past, programs were all doing their own thing, but now KDE provides that information as a service. With a standard API. So you can have two programs installed that manage your contacts, and they're both using the same list of contacts. Same with your calendar. Back in the day, if you used two different programs to store contacts, you would have two databases of contacts.
Calling that bloatware is just stupid. It's literally a core service that a useful operating system should provide.
In addition, learn how to use Google instead of posting in the forum like this. It was trivial to find out how to disable it permanently. Trivial! Asking us to do your work for you and then tacking on a "conversation starter" at the end doesn't make your post any more palatable.
Here's your answer: