Whilst I accept that language is a fluid resource, and it does change with time, I do get a tad (modern americanism!) frustrated with folk saying that Shakespeare would not understand us. He lived centuries ago, when most of the population was illiterate, so as reading and writing spread, there was a gradual concensus as to how words were used, which words were used, and grammar (def: knowledge or usage of the preferred or prescribed forms in speaking or writing) started to be established.
What bugs me, and many others here by the look of it, is the drastic deterioration since the education sector found an excuse not to be teachers, with claptrap theories about "self-learning", "discovery" and so on.
If the same theories were applied to driving a car, and pupils were just sat behind the wheel and encouraged to "just go ahead, explore, find out what does what, learn by experience" as happens in formal education, we would soon have carnage. Of course it would also be forbidden to test the pupils with a test, only wanting them to hand in some course work, like crayonned drawings of a car, to qualify - and naturally nobody would be allowed to fail. The proponents would then wait a suitable period before claiming success, pointing out that there was far less traffic on the roads - ignoring that this would be due to a massive decrease in the living population!
In my working life I have successfully trained many people to operate printing machinery, from spotty-faced Youth Training Scheme teenagers through to one lady in her 60s, and found the Tell & Show/You Tell Me/You Show Me method to be the only viable one. That is, I demonstrate the task, explaining and verifying each step with the trainee, then get them to tell me how to do it while I carry out the actions (which implants the concepts and removes the initial fear of doing something wrong), then get the student to do the task - checking for thorough understanding and agreement all the while. It was hard work mentally, required preparation and concentration, and was effective - which is why the poorly-educated jumper-wearing call-me-by-my-first-name so-called teachers of today will not do it!