Well, at least primarily rely on a map. I do tend to carry a compass in less familiar/more challenging situations but for hiking on trails a map by itself will generally do the job.

Some people are talking about situations that would be very challenging without GPS--low visibility/no trails--and I'd just say that I'd definitely want backup in those conditions. I wouldn't want to depend on a single phone.

Which I still personally agree with. Until recently GPS has been a pretty expensive tool. Even now, a dedicated device costs hundreds of dollars and typically require subscriptions. Your phone also isn't going to be reliable since its battery life is extremely limited (especially when people forget to turn off their data and so their battery drains even faster than expected). This is probably the dominating factor in that recommendation. If you are going to rely on your phone for navigation you BETTER have a backup. If you are going to rely on a map, you SHOULD have a backup, but it isn't necessary. They are going with the safest option because they recognize that people will typically bring only one form of navigation. The only thing I'd change is removing the "only" and "at best" part from your quote. "Primarily rely on a map and compass, your GPS is a backup."