"That doesn't count...you cheated....you used loops...". I overhear things like this quote everyday from my 10th and 11th grade Audio Production 1 and 2 students where I teach. One students prides himself on making everything himself while another student is left feeling like he or she has to defend themselves because they used loops.
My thought is always "Who the freak cares"!?! I have heard music using loops that was dope and I have heard music using loops that was a train wreck...and vice versa for the "i played everything" crowd.
There are pros and cons to both approaches and at the end of the day I don't think it really matters so much. Music is about creating and having fun. The obvious advantage of composing originally is that your music may differentiate itself from competitors more but that doesn't guarantee success or quality. For what you may have gained in originality and independence, you lost in collaboration and time.
Working with loops in my book is the same as working with a co-writer. What is the difference in me using a 4 bar guitar riff from a sample pack and invited my friend over to play the 4 bars himself??? Hmmm, hmm, hmm? The downside to using loops is that it can handicap you if you rely on them too much. What if you find a sound you like but it's not exactly the way you want it? Having the ability to identify the key of a piece of music to compose something that will supplement or compliment it should not be overlooked or undervalued.
In conclusion, whether you the main part of your song is a loop you snagged from Logic pro, like "Love in this Club" by Usher, produced by Polow da Don, or you choose to play keys or multiple instruments yourself like Ryan Leslie and Darkchild, or you choose a hybrid approach where you incorporate elements of looping, chopping samples, and composing....just be GOOD at what you do!