Japan, South Korea, Oceania server battlefield has a player who often maliciously hangs up and reports useless. What other ways can Blizzard submit a report?
Report them through an in-game report (AFK/Uncooperative) is the only way. Whether it is useless or not, you should just keep reporting those AFK and Griefers instead of doing nothing at all.
Complaining at world chat or Discord or Reddit or Forum is less useful than reporting them immediately. At least there is a small chance that they may get punished if the DI team feels generous on that day and check the report.