Yup, while many people do like this feature (the billions of people who use WhatsApp and breathe a sigh of relief that they can find their friends & family on the app without having to manually create a whole new contact list), obviously there are others who do not (irrespectively of privacy concerns). The point of the blog post is to show we're trying to cater for both, rather than assuming that everyone falls into the WhatsApp bracket.
If you are trying to cater to people that will use your app like the other services, then why would they just not choose Discord or Telegram in the first place?
The goal is to make it easier for those people to use Matrix too. Otherwise you won't ever expand past a fraction of the tech community and won't overcome the network effect of larger messaging systems.
This is the same reason why (for instance) E2E isn't the default right now -- there were massive usability issues that most normal users would have trouble with (until very recently you could lose all your historical session keys unless you were very careful and backed them up religiously). Speaking anecdotally, several people I've switched to Matrix really wanted to switch away because they lost all of our old chat messages when they logged out of their account.
I hope you agree that people without very strong privacy concerns should be able to use Matrix as well.
