You wouldn't need to spam it 24/7. You would have an entire week to get the rank you would want. Then, if you want to get more rewards over time, you can easily do so. If they introduced rank decay, people would just wait until the end of the season before they start grinding to avoid that. Players would not be locked out of PvE content, because it would only be one week as opposed to several weeks with the current system. If it resets every week, there isn't as much of a pull to sell ranks since you have an easier time to get them. There's a higher volume of rewards, meaning that there is less pressure to grind it consistently without FOMO.

I'm speaking from the perspective of a former Elder Scrolls Online PvP'er. ALL of their PvP rewards reset weekly. It promotes competition and involvement because it is now attainable.