What you mean pointless? Fivb put a big points for VNL so that other countries will take the league seriously. So if the team won't participate and have poor performance in vnl the result will definitely affect the world ranking and for the next olympic cycle. Also this is the only National team league they have for almost 2 yrs. Isn't it also beneficial to the team and evaluate what they need and missing to win the OG?
There is 2022, 2023 to worry about that. The most important thing for any qualified national team is the Olympics this year.
I assure you that Serbia, for example, do not care they are ranked #6 or whatever in the world.