Follower counts are an important feedback mechanism and help keep Nostr content quality high.
Follower counts (as inaccurate as they are) are still an important metric that signals reach and the impact of your content.
If your follower counts are low to dropping, it is a market response telling you that maybe your content sucks and you should improve your signal/message/content.
In summary, follower counts help improve the overall quality of content on Nostr by providing a feedback mechanism