This is your intro thread - start a build thread and you'll get more info. Not everybody hits the intro section, in order to provide technical information, on a routine basis. Nobody is gonna build your rifle in this thread. You'll thank me later.
As to the "why" - there are a million "whys" on products. Some of the product research is going to have to come from you. You're not going to always get a product recommendation, and get a big list of "Whys" on that product. Making that a stated requirement will definitely hinder your responses. Example - if I like a certain product because I've been using it for years, and it just works, but you want me to tell you why I like it - I may not put in the effort to tell you. Hell, it's well known, never had a bad reivew, and I might not feel like listing a bunch of information that's already available almost everywhere you turn on the internet. I'll just skip answering, and let you do the legwork.
Just a tip... People recommend things - research what they recommend, and come up with your own "why-nots..."