Order of postrm and postinst can cause service disablement and other side effects
When packages are replaced (for example because it was renamed) and they provide same init script it would make sense that such init would stay enabled. The problem is that this does not happen and most problematic is that it does not happen even with packages that are enabled automatically. This is because
postrm scripts are executed after
postinst script. Install script first activates already activated service and remove script later disables it.
The real reason is an ordering of packages. We should order removals of conflicting packages before their replacement.