No thanks, your infraction history is also important for determining if you're actually becoming a better user. Also, there is a significant difference between people who have been around for 5 years if one has 10 pages of infractions and one has no infractions at all. As an aside, those people do exist.
Your average person does not have that many infractions. 10 pages of infraction history means that that person has consistently been in violation of the rules, and with 10 pages it is almost impossible for them to not have violated exactly the same rule multiple times. In short, it is almost concrete evidence that if we have an issue with a user, us telling them to fix it won't result in it getting fixed. Most users are actually decent people though, and if we explain what they did wrong and we ask them to not do it again, most of them won't do it again. These people will almost never get more than 2 pages of infractions, no matter how long they stay in the community.
We do check dates on your infractions when you apply for a staff position. If you have 10 pages of infractions, we probably know you by name and reputation already, so we'll know if you've been active. If your most recent infraction is thus still from over a year prior, we will generally assume that you've completely reformed and we have, in fact, given people in this position a chance. Sometimes its even worked out well.
Generally though, if a user has gotten up to the 10 page mark, even if we did delete their infraction history they would just get another few pages the next time they were active. This is a fairly strongly indicated trend we've seen, and it doesn't vary as much as you might think it does.
We do give people with horrible infraction histories second chances. But, as evidenced by their horrible infraction histories, they don't usually use them very well, so why should we purposefully make it harder for us to ensure that they're becoming better users?