i guess OP asked about seo not seo applications :SYes you can relay on SEO application, it is a very powerful tool and lot of people out there are optimizing there site with SEO. But the most important part is you have to understand the power of the SEO tools in order to use it effectively. And if you are using proxies, I recommend you to use private proxies instead of public proxies in order to avoid spamming
Honestly what else is there other than PPC that is as reliable? Social traffic sucks for most niches, and depending on 3rd party sites for piping traffic is tough to throttle up to reliable rates. I don't see how it isn't advisable... honestly my mind is blown people are even saying that.
What's Else You want to Rely On? SEO is One Thing On which if You Rely, You will never fail.