The title tag allows Google to determine what your site is about. Although Google now is more user-experienced based than before, it would not hurt to place a Title so as to let Google know what you site is all about.
To better illustrate, please see how useful a title tag:
To make a point, I have gotten a Thai site (https://www.hlthailand.com/) – so that you will not know what this site is all about. The title tag would be easier for online users (in this case, Thai) to know what the site is about. Still, the domain name is still missing a complete title description but imagine if there are descriptions on it that would properly tell users what this site about.