Article submission was never and will never be a thing of the past for SEO. And if anyone tells you otherwise, you can make out that they are not well aware of the world of SEO.
While it is true that Panda and Penguin changed the landscape of SEO as you mentioned, but taking a closer look at how these algorithms work will give you a better understanding of why your site might have been affected.
Panda was aimed at removing sites with low quality content. It was designed to provide better ranking to the sites who have greater in-depth quality content as compared to sites with low quality content or sites with content which is not in -depth. Also, if your site is affected by any of the Panda updates, it will take a while for you to see the change in ranking of your page after you changed the content of your site. This is because, the crawlers will come to your site at a later time and update their results.
Penguin was designed to punish those who had bad link references from low authority sites. So, if your site had links which are not good quality sites, then you will be affected.
Keeping that in mind, article writing is one of the most valuable thing that one can do for their site.
Hope it helps