Keywords research is dead. Long live subject research

Keywords research is dead. Long live subject research

It has been clear to me for some time now after the Google Rank Brain update that Google search stopped relying on keywords to figure things out and actual rank websites.

In turn, it has taken a new approach, figuring out how well you talk about offering content on a complete subject and ranking you accordantly.
The "subject" itself might contain a lot of different keywords, some similar in form and meaning, synonyms or other keywords that are totally different.

For example, if you are talking about a certain medical condition, chances are you will find a lot of close variations, synonyms, and popular terms. You need to show Google your content haves it all, that its talks about the whole subject and the user doesn't need to make additional searches to find whatever he or she is looking for. Also, for the certain example, you may also need to include other subheadings like "treatment" or "symptoms", all this is expected of you by Google and if you fail to deliver Google will rank you accordingly.

So if Google is already processing everything in terms of "subjects" why are the majority of SEO gurus still tell us about "keyword research"? In my opinion, we need to take thing to a next level and make "subject research" instead.

What do you think?