What the term always covered
Proactive security predates every current acronym. The idea is old and simple: spend effort reducing the chance of an incident, instead of organizing the house only to respond well when one happens.
In practice the umbrella was always wide. Patching before exploitation, configuration hardening, permission review, threat hunting inside the network, penetration testing, training people. None of that has a sharp boundary, which is why the term aged without ever becoming a product category.
Posture is not the same as timing
This is where the market created confusion.
Proactive describes posture: the organization cares about prevention. Preemptive describes timing: the action happens before the attack starts, not after the alert.
A company can hold a clearly proactive posture, with a mature patching program and an annual test, and still discover a new asset three weeks after it appeared on the internet. Good posture, bad timing.
That gap is what the analysts went out to name. The term they picked is preemptive cybersecurity.
What actually changed, and what only got renamed
Cadence expectations changed. A proactive program from the 2010s ran quarterly and counted as good. That fails the test today, because the surface changes every week and the adversary automated the search.
Validation expectations changed too. Detecting the flaw used to be enough to open the ticket. Now you are asked to prove the flaw is reachable and exploitable on that asset, because the queue grew too large to work through.
The goal did not change. It is still reducing the chance of somebody getting in.
Where to start without changing tools
The first step for any proactive program that wants to become preemptive is an inventory of what is published, refreshing itself. Without that, everything else works on a list that is already wrong.
The second is to stop ordering the queue by theoretical severity alone and start crossing it with known exploitation. Neither of those requires buying a new category.