The seal is not important to the user, but is important to the community of developers who advocate for W3C specifications, but does not guarantee anything.
Some websites use W3 Consortium stamps only to promote new specifications such as HTML5 and CSS3 (W3 personnel themselves encourage this. Stamping on shirts, brooches, stickers, etc.), others misuse to show that they adhere to the new standards of specifications, others, most of which use, really are compliants with the new technology.
With the advent of HTML5, development began to worry a lot about accessibility, emphasizing, for example, the semantics of HTML, turning technologies to the user, so developers can shape better experiences for them.
Stamps are not about the speed of traffic on your site or application, but about the accessibility.
The Internet is the most democratic space you will ever find, however, developers still sin a lot in relation to access universal.
You shouldn’t worry only about "running", but also about "running for everyone".
How a screen reader will behave when entering read your website?
It is difficult to strictly follow the HTML5 rules and the new Web technologies that accompany it, and that revolutionize the Web every day using a framework, which is essentially generic in the vast majority of cases.
See the website of The Paciello Group, on accessibility.
Accessible Culture
Read more about the use of stamps on HTML5 logo home page.
Learn how to use a tool like HTML5 Outliner.
You can use as many stamps as you want, but we users will only care about one who says "secure site".
The average user is not interested in how the sites were made, rarely will link the technology used to security or speed.
Look for more about Philippe Le Hégaret.
I hope I contributed to the discussion.
The stamp does not, so much so that you don’t see it around. There are some things that are required for it that in practice are bad. Making it light, standard, in order is a good thing. I don’t like framework and be light and use framework It’s usually antagonistic things.
– Maniero
@bigown, I agree with you, can not be light and use the bootstrap, I use it for ease in various aspects, not had big problems until today. But after that, I’m thinking about rethinking putting everything together from scratch, without relying on any framework. I always said it was for the lazy, and I fell into the trap...
– Hebert Richard Masseno Dias