Why and what to learn on guitar

I have seen many people who just pick up the guitar and follow just the opposite path to their goals. And their are players also who are trying to learn so many variety of things but they don't know where and how to use it. Even they do not realise that they don't need to learn it for the kind of stuff they play. They are just learning it because they heard somewhere that it is a cool thing to learn. And yet there are players who are so much specific and arrow pointed that if they wish to play Hotel California, the first thing they will try on guitar is a B minor chord. I wish I could gift them some patience.  If your sole goal is to play some rhythm over some of your favourite songs, you should not learn scales. Because scales are not required for that. You should also not waste your time in learning the notes on the fretboard. Yet you should not just neglect everything like the finger exercises.
So the question is what to learn.
Regardless of what you want to play, you should not ignore the finger exercises. Because dexterity is a must to be able to play stuffs fluently. And a good picking technique too. And you should at least know the notes on the fifth and sixth strings cold. After this you must know some of your basic open chords and some strumming patterns. And if you want to, try to learn the bar chords. They will be very helpful. So this is all required to play and sing a sweet song on the guitar. Remember the order in which I have described them, and stick to that. Now if you want to learn more and develop yourself like a pro on the instrument, then only you need to learn other things like scales, modes, arpeggios, and more. So if you just want to be able to play few songs, just follow the above sequence of learning. And you will be happy forever.