

They made an announcement on their Steam event page, which goes into more detail as to why they did it this way.
Previously, we offered free Key applications to replace game versions for existing players. However, as of this month, the number of supplementary Keys distributed has exceeded 30% of the total sales volume prior to this initiative—and we still receive numerous feedbacks from players stating they haven’t received their Keys, along with complaints about slow email response times.
They made an announcement on their Steam event page, which goes into more detail as to why they did it this way.
Which you can find here