One thing I don't understand about cooldowns is that it seems that if everybody uses cooldowns then there is no effective cooldown. Then you ll have to keep increase the cooldown period to get the advanatage...
there are parties that don't want that cooldown, libraries or software writers. XZ utils backdoor are found by Microsoft and Postgresql developer Andres Freund due to high CPU usage (or latency? CMIIW) during SSH tests, those are the people who will keep the same workflow.
The admins of the hacked project are likely to notice the hack in a day or two. Malicious actors are a separate concern, but hacks can be mitigated with cooldowns even if everyone was using them
The primary benefit of cooldowns isn't other people upgrading first, it's vulnerability scanning tools and similar getting a chance to see the package before you do.