urls, canonical, no duplicate

[FlashRebel]

I think well urls, linking, canonical without duplicate links need to be in first position now.
Features in Joomla 3 are great, responsive, bootstrap design, tags and other features, like working on media manager and other things ... but nobody will see it if our sites have duplicate links, wrong linking, bc. search engines will not showed our bootstrap, responsives websites with tags and other features.
I know there is some good extensions for SEF, maybe 3 of them working well, but with some other extensions not always works well, also bc. these sef extensions some website can not be updated, while sefextensions are not ready for it.
Is in community some works now on canonical, urls without creating duplicates ?
Urls are core of each website.

[stutteringp0et]

I've never seen Joomla core SEF create duplicate URLs. It's a very stable system, in my opinion. Maybe you're having a problem with the SEF implementation in a specific third party extension.

[RedEye]

His point is/was that you can create endless url combinations who do all point to the same article.
J!3 doesn't fix this, but it includes rel="canonical" link, but J! creates 3 different versions of that link.
mysite.com/index.php/test => <link href="http://mysite.com/index.php/test" rel="canonical" />
mysite.com/index.php/2/1 => <link href="http://mysite.com/index.php/2-uncategor ... some-title" rel="canonical" />
mysite.com/index.php/1 => <link href="http://mysite.com/?id=1" rel="canonical" />