There are literally thousands of stocks out there and there is absolutely no way you can go through all of them before you make your final decision on one and you want to actually invest/trade the company.  Even if you can perform solid due diligence by hand, why waste your time when you have stock filters and research tools that help identify the good companies from the crap.
Assuming you already use stock filters and research tools, when you compile that list of companies that meet every criteria you are looking …