If the O line can't protect him and the WRs can't get open, Fields must either throw the ball away or try to stretch the play to make something happen. So building a good O line and a good set of receivers are important to his health. Remember, he has a tendency to hold the ball too long and has been injured multiple times in college and last year with the Bears.
Most WRs and O linemen take a couple of years to adapt to the pros, so waiting until next year to draft them, probably means they won't really excell until 2024 0r 2025 You also have to expect injuries to linemen and WRs, so depth is key. So it makes sense to start now addressing areas of weakness if you want Fields to stay healthy.
I understand people on this message board like to respond with insults. Hopefully, they will learn it's OK to disagree without them.