Again, please provide where Cosmic Raven says to stay in any era forever, otherwise please do not provide false information on something you lack knowledge in.
Camping isn't about staying forever, just more than "typical", though that is a bit subjective to some degree. It's certainly not wrong to camp, it's just that other people tend to not like it and some others consider their opinions to be Inno's intent or "the right way".
I used Cosmic Raven's strategy almost two years ago when I first started the game and it was outdated then. This game changes often based on new things that come out. It's probably best for someone who is very new and just started their village as they don't have access to many of the event buildings that change the way you can approach that strategy. But at some point you will find yourself- for more than one reason- having to deviate from the guide.