I think the issue is that people feel pks only come for the reward after blues have done the work. I've never been raided when I pop a champ only once champ almost dead....
Kyronix did state there would be some type of reward but left it at that. Prior to Power Scrolls what rewards did PvP have other than bragging rights. I find it amusing that people keep throwing this "Risk v Reward" around when in pre pub 16 the Reward was the betterment of your skill at PvP, It was the PKers that dry looted the weak and brought about the creation of Tram. It was mentioned that they really didn't want to recreate the PK side of Fel so if you pick the Tram rule set you will be safe from players but not the MOBs.
On LS they will kill you as soon as they see you even if on level one. Then they hang out waiting for you to return.
Pure pk for griefing purposes.
When Champ Spawns first came out--when the idea of "Evil in a Can" came out, for those who were heavily invested at the time--it was a remarkable idea that attracted EVERYONE. The first Champ Spawns would easily have over 30 blues involved from various guilds. Early on, there were not organized PvP/PK guilds (raiders). There were so many unorganized blues (spawners) and so few raiders that the spawners would generally ward off the raiders. Once the value of power scrolls was assessed and people began to organize for control, however, the unorganized blues fell fast.
Control worked in a few ways, which are important to understand for those whom have only been spawners (or farmers, even), or those whom have not participated at all. I would not look at it as PKing the way PKing used to be in the traditional sense. For example, people used to EXP/FS in pairs to off people in guardzone, and without anyone to call guards for them they would get away with it. That, to me, is the more aggressive form of PKing. Or those would would follow you to an Orc fort, or those who would kill your miner, or put a blade spirit in your house (the list goes on and on). Spawns provided an objective control that was different from the more traditional ways of PKing, and they led to an organized PKer community in a way UO had never seen before.
1) PvPers were, at that time, not always built to PvM (or PvE). There were not established Sampire builds and tamers were not yet all on Cu Sidhes with...let us say..."enhanced tactics" outside of what the gaming mechanics should have allowed, with bokutos, and so forth. There was a clearer division between what it meant to be a spawner (blue), and what it meant to be a raider (PKer). If the organized PvP guild did not have access to a large enough amount of spawners they would use ghosts or stealthers to monitor the progress of a spawn then make a decision. If the progress advanced to a point where they felt comfortable they could finish off the boss, they would raid. If not, they would wait.
2) Organized guilds began to fight each other. Each organized guild would have both spawners and raiders to accomplish control. The raiders would protect their own spawners after a successful raid, and enemy raiders would try to break down the defense and get control back. Guilds that did not have both spawners and raiders were at a disadvantage because control required people to become murderers (reds) or to make the most of being gray/less than four murders.
3) As more competition arose and people looked at UO.com Guild rankings as a marker, non-guilded or disorganized blues fell off, and as UO progressed and released easier ways to both PvP and PvM, such as tamer hybrid builds based on Skill+ items, and so forth, and item caps that were much more easily met, the difference between the need for specialized spawners and raiders fell off, too. That made it easier for individuals to PK earlier in the cycle.
4) Scarcity of targets (blues) is also a factor. As power scrolls became less desirable due to less demand and as people moved away from competition, raiders began to raid earlier just to kill people, even if it meant they would not be able to complete the spawn themselves. They were doing their part to control the spawn and they would wait to see if others would sign in later to help finish the spawn. By that point, they too were a bit apathetic, given the market (other than the big ones like 120 magery and 120 taming, and so forth) was less desirable for a great majority of the scrolls.