What statistics do you have to back up your point? At the time of writing only 25 users have hit the reputation cap every day this week. That's 25 out of 1,201,667, i.e. 0.00208% of the user-base so I don't really see where you got
"fairly quickly and fairly often" from. Personally I've never hit the reputation cap on Stack Overflow; the most I ever got in a single UTC day was 190.
Not only that why would you want to disallow newer, and equally qualified users, from achieving what longer term users have been able to do? You're advocating an entrenchment of privilege for a reason that I can't quite discern from your question.
If you're talking about sock-puppets and / or serial-voting then it'll be reversed automatically.
As accepts and bounties are excluded from the cap would these be included in your new one? If not then your idea has huge holes. If so then how would a new-user be awarded a 500 bounty for a fine answer? How would this answer have received the accolades it deserved? A user joined Super User to answer a single question (thank you Sathya for the link!). Is that suddenly worthless?
There are other instances of users posting a single amazing question as their first. Are their contributions worth less than Jon Skeets because they only recently found out about Stack Exchange?
Most of these questions are rhetorical. If a new users contribution is worthy then it should be worth as much as an equally worthy contribution from a very established user.