Odd because I've been lifting for years and I've wound up with large arms simply by doing lots of compound pressing and row work. I don't do any isolation with the exception of leg curls and leg raises at low weight with moderate reps at the end of my workout to get blood flow for recovery, and my arms have grown fine with the rest of me. The fact is that triceps make up most of your arm size anyways, and bicep curls don't do much for your total size. If you're doing enough row variations, your arms should grow.
I'm not against isolation movements or barbell curls, I've just never seen a personal need for them and I don't have stick arms. I certainly don't see any need for isolation exercises like curls in a beginner program like 5x5. You should be spending that effort doing squat/deadlift/bench/press instead. It's a much more valuable use for your time. As you progress into an intermediate program that's when I would say to start adding the accessory work for your weakpoints and the isolation movements for the aesthetics.
If you want to look like a bodybuilder or do "powerbuilding" then you need that base of strength to work off of anyways.
