the absolute necessity of a guru

  the absolute necessity of a guru,''

is there, and it is being ****lfilled in nature, universally, continuously, nature has provided the tea****nd learning process and abilities internally, and externally .your examples clarify this.
''But as the learner 'grows', it moves away from 'teacher centred' to 'self centred' (book or computer centred?) way of learning.''
true , as the teacher and learner grow
1  need of external till the internal is kindled adequately
''aavo sadguru mere maname,
antharajyothi jagaavo swaami''
2  many gurus have success****lly made themselves dispensable, u****udio video
3  students now can learn things at desk top
4  the tendency of nature has been to make the beings as much self sufficient as possible, investing in to them enough intelligence from generations to generations, keeping the need of external teacher to the unavoidable bare minimum, for human in the form of conscience, the internal guru
''by watching others''
ie from external guru
'wanting' to swim. Nobody initiated
ie from internal guru
'Incidental learning, more enduring than formal learning'
learning endures by practice and teaching to others, no matter how learnt
we can take 'formal' as teacher cantered learning[external]and 'incidental' as teacher-less[internal]
Again, both you and I, (for that matter any two persons) can be a teacher to the other, making the learning faster by holding a 'thought mirror' to each other.
excellent perception, [good absorbers are good radiators, a law of heat transfer]
my teacher said, teacher learns from students more, than they learn from him , this is highly dynamic process of give and take
no one is a student or teacher exclusively, permanently
In all fields, including the so called “spiritual” this appears to be happening.
definitely, satsangs/spiritual interactions/discour​ses/book reading are consciously encouraged to accelerate this process
''If this point can be cleared, perhaps, a lot of traditionalism that prevents progress .. can be swept aside''
a master when tried to be modern to reach his knowledge to more and faster, a lot of traditionalism in those days did raise objection, which the master fortunately did not heed, the result was globally seen.
''Evolution might be the better word. But are we sure of all the nuances of the word?''
as i understand, Evolution is the word=prakruthi parinaam, better and better design of the species as generations pass, recycling the feed back of experience, to make them much more sustainable