|Naver login page, with SNS login options|
I say "first step" because you will be prompted to fill out your profile details fully, as you would be required to do if you joined via e-mail address. For that you'll need to add an email address and mobile phone contact to receive an SMS text message verification code.
You can postpone all that for a while and use this SNS-linked account for most Naver services, (I tested it out with a dummy SNS account), but at some point (took about a week for me), it will require you to finish the proper sign-up. Seems like a way to lure you into signing up the normal way.
To be fair, adding an email address and a mobile number (it doesn't have to be a Korean phone: any number will work) isn't too much to ask. Of course you won't be able to fully utilize services like Naver Pay or other money-related activities, but the "email & phone number" account will work fine for utilizing most all the non-pay services. At least, I haven't had any issues with my Naver account, but to be honest I don't use it all that much anymore.
I can remember when the sign-up was all in Korean and we needed screenshot tutorials explaining step-by-step how to get a Naver ID. Now all it takes is one click with your Facebook. The foreigner-friendly march at Naver HQ continues.
Try it yourself here: