A chat admin can still send you a private invite if he/she drops you the invite link via personal message, but the best part about this is that the said invite will disappear after three days, so just close one eye lah. 

Of course, Whatsapp isn’t merely doing this to make your life a lot more peaceful. It’s part of the company’s initiative on combating the spread of fake news. The feature is now available for BOTH iOS and Android, so you might want to start customizing who can add you and who cannot.