I think this is what the guys mean - check ezinearticles.com traffic movements for the last 2 years (you may need to adjust the date on the chart)
semrush(dot)com/info/ezinearticles.com?db=us (sorry, I can't post links OR images yet! Check that link tho, replacing (dot) with . - You'll see what I mean!)
^^^ If someone with enough posts can take a screenie of that traffic nose dive and post it below, that'd illustrate what folks here are saying nicely
It takes a FAST nosedive!
If the article sites you submit to allow mass submission (or articles that have been submitted en-mass to other sites) it's likely they'll see similar traffic drops, if they haven't already.
- If you're doing this to build links for rankings - I wouldn't bother
- If you're doing this for traffic AND that traffic is converting for you (either bottom of funnel OR top of funnel WITH some movement of leads towards conversion) I'd understand more, however I'd still worry about the future as if that site loses it's rankings and traffic, or gets spanked by the Panda AND if a lot fo your backlink profile is from such sites, you're going to risk seeing negative effects (EITHER as a penalty OR just as a loss of backlinks - lower weight of backlinks).
Efforts would be much better served going towards really cool content on the site,
building a list from the traffic that pulls and using social to engage with both customers and other industry bods - building relationships, IF DONE RIGHT, can lead to MUCH better links... Try to get friendly on social with a few known authors on
big industry sites and good things can happen... Seriously

I'm not promoting 'social engineering' exactly, but not far off! It's surprising what can happen when you make friends in the right places

Gotta be genuine tho.