Not all out of the box solutions work out of the box. A great many need fine tuning. What happens when you need to troubleshoot a theme, or make it responsive, but don't know how? Who do you ask?
It took me more than a dozen iterations through setting up and configuring WordPress, several years of troubleshooting, reading, researching, trial and error before I could truly say I knew what I was doing. You can experience the same learning curve. I encourage it really. Or you can have a professional handle it for you and start off on the right foot far sooner than any DIY installation.
I can't tell you how many people have tried customizing their own code / theme on WP, then upgraded their theme, accidentally deleting all their code. (Hint: WP pros use child themes or develop their own.) I can't tell you how many times I've seen people install conflicting plugins, breaking both, and not knowing what to do next. I can't tell you how many times I've seen very scary security breaches from people who set up their own sites (pretty much everyone who sets up their own site leaves their pants hanging down, totally open to hackers). Or sites that load so slow that it boggles the mind... situations that could be solved by some quick minification and gzip.
Web design is a profession. You can DIY, but if you want professional work, you need a professional. Or become one (a professional web designer / developer).