I just used the following button out of curiosity and I don't understand the purpose of it showing notification on everything the other person does including likes,comments etc. I believe that from what I've seen in all other social media platform, the purpose of the following button is to make it easier for two people to interact by recommending and showing the posts of people we follow and not spam us with notifications of whatever the other person does with his/her personal account and I don't think a good majority of us might not like our notifications filled with other people's comments or likes that they did on some other people's post which we have no connection with. I just tried it now and the update was here since sometime so maybe I guess people don't find that annoying as they are used to it