SEO's from the early days eventually learned that no matter how often they submitted URL's to search engines, the rewards were questionable, if any existed at all. There are still some search engine marketing company rip-offs selling site submission services to "hundreds of search engines", promising rank (in them all?) and doing it for dirt cheap.
When someone asked about such a scam, he also wondered that if a search engine like Google follows links to find new web sites, why is there a URL submit form?
It's kinda like a Dentist insisting that you get fluoride treatments, even though you buy toothpaste that has it in there and many towns put it in the water and some research says it's bad for you.
Do you submit to search engines on a "just in case" basis or is there some worth to this practice that remains?
If you're curious, read How Many SE's Do You Submit To? at Cre8asiteforums.