I somehow misread your thread (sorry about that), so I hope this will answer your question.
So, how important is designing a website before coding? Well, that depends on who is creating the website and what is the situation. This is a question where the answer isn’t really straightforward.
It is not important(ish) if you only code and that’s it (whether this is in a professional environment or not). It is very unlikely that you will use a design software as well. But, it is beneficial to know the very basic of some design such as layout since you will need to work with it in coding
However, to answer how important it is to design before coding if you are in a situation where the design aspect will be involved actually lead to more questions.
Are you the person who can visually see how the website should look and able to deliver that vision without using the design software.
Even if you answer the above question yes. Maybe that is the case when it comes to creating a simple design layout. Like myself with my tribute page project, I only needed a paper and pen and draw it all out roughly because that was a simple design layout.
But, are you able to do this on a higher level of artistic designs such as where it will involve illustrations and customisable button designs?
In conclusion, it is up to the individual to design before coding as long they are aware of if they have that ability to create a successful web layout.
I hope this will answer your question?