Oh God, where is the validity?

Erupted there discussion on validity. Rather, the essence there was that the development of IT in (and no need for indignant sighs here!), In Ukraine, I say, is behind the entire planet. But somehow they quickly forgot about it, and the question turned to another plane.

Validity or not validity? That's the question.

What is this fanatic desire for valid code for? What are its practical advantages, besides the fact that it is a standard in principle?

Here "Habr" is not valid , for example. And what, let's all together stop hanging out here. She’s not valid!

In short, you need to think about users, not about the image. The user will be satisfied - there will be an image.

Update
Thanks to everyone who noted in the comments. Reasonable explanations are only good. To me :)

True, I did not mean that the invalid Habr is bad. But that's another story.

Update2
A kind of continuation of the discussion novikov.habrahabr.ru/blog/5404.html .