the article is about not using email.
no tool is perfect. you know what would be great? if hammers cured cancer. they don't though, so we just use them to hammer nails into wood.
speaking to people in public places is also a way to communicate, though equally bad for privacy. if there's nothing you can do to change the privacy attribute of "speaking to people in public places", does that mean you should never do it again?
or: use codes that only you and the other person know, hold hands and tap morse code into each others palms, find secure rooms.
people get upset when one tool doesn't do all the things they want, but its a weirdly tech centric thing.
"your startup doesn't do X so i'll criticize it". you can play the "need more features" game ad infinitum -- but nobody criticizes cast cups for their failure to keep drinks cold indefinitely or couches for failing to give them back massages.
Because a feature makes a tool better doesn't make it a requirement for its usage.