Cannot get modern team sites with REST

Apparently, this subject has been up for discussion before. I found this post which describes my problem in a nutshell. A modern team site uses GROUP as  web template and above mentioned post had a solution. Thanks.

The solution in this case was to use a web service instead and call it with a good old XMLHttpRequest. Here's a sample if anyone else have the same issue.

  var xhr = new XMLHttpRequest();
  xhr.onreadystatechange = function(){
    var followedSites = [];

    if (xhr.readyState==4 && xhr.status==200) {
      var data = JSON.parse(xhr.responseText);

      for(var i=0;i<data.Items.length;++i){
        followedSites.push({
          Acronym: data.Items[i].Acronym,
          Title: data.Items[i].Title,
          Url: data.Items[i].Url
        });
      }
      console.log(followedSites);
    }
  };
  xhr.open('GET', this.context.pageContext.web.absoluteUrl + '/_vti_bin/homeapi.ashx/sites/followed?mostRecentFirst=true&start=0&count=100&fillSiteData=true', true);
  xhr.send();