For example, all the packages I'm building for the first time in epel8...

Even outside of new packages I rarely get karma for my Fedora packages, much less for my EPEL packages and two weeks is a "long time". I have some upstreams where I have to skip releases because they update within the two week period and the policy of obsoleting an update when a new one is created would mean they would perpetually be in testing and never make it to stable.

Perhaps it would be a good idea to let the maintainer determine if a previous update should be obsoleted or not when pushing a new update?

Thanks,

Richard