Hi @rover8200 and everyone!
My name is Diogo and I’m on the Trust and Safety team. I hear your concerns and would like to try and help 
First, as several people mentioned in this thread, the main reason why Patreon doesn’t allow benefits that involve any sort of gambling is due to laws and regulations regarding gambling, in the US and internationally. We also do care about and work to ensure there’s no scammers/scams on Patreon, but that is true beyond raffles and gambling and is a whole issue in and of itself.
Like @Temrin mentioned earlier in this thread, we published a blog post in May where we shared not only more details about our stance on Raffles and Gambling as a whole, but also several suggestions of alternative benefits and contests creators are allowed to run. There’s some pretty cool stuff in it, if I can say so, so be sure to check it out 
: Patreon’s stance on raffles, lotteries and giveaways.
Regarding the idea you mentioned:
Imagine someone becomes your patron today. You already have many other patrons. How long would that new patron need to wait to get that benefit? 1 month? 10 years? If it’s unclear, it becomes a matter of chance whether someone stays your patron long enough to get that benefit, because they can’t know when that will be. In another scenario, you gain two patrons in the same day. One of them gets the benefit after 1 month, the other after… well, they’re still waiting… This allows the first patron to make a decision on remaining a patron or not having already gotten the benefit they wanted, while the second patron is “stuck” waiting for a reward they don’t know when will come. You see how this still adds an element of chance to your patronage?
As highlighted in the the article shared above, there are multiple ways in which you can reward your patrons if you only have a limited quantity of a certain benefit. Here are some ideas:
- Make it clear and consistent how long it takes to get that benefit. For example, once a year on the anniversary of the date each patron started supporting you (or a different time frame).
- Create a higher tier limited to the number of items you can give each cycle, or limit an existing tier to that number. This way, every patron on that tier is certain of receiving that benefit, and every patron not on that tier is certain of not receiving it.
- If that benefit is not very regular (maybe you only get products once in a while), you can instead create a Special Offer limited to the number of items you can give as a benefit.
- Create contests where patrons can compete to win the benefit(s). You can decide how the winner(s) is/are decided, as long as the criteria for winning is/are clear to everyone participating and is/are not chance based. Now, you can indeed still decide behind close doors and away from ours and your patrons’ eyes that you’ll pick the winners randomly, but I would hope we can find a solution that everyone can be happy with - you, your patrons and Patreon
We do 
but because we want to help you and every creator understand our Community Guidelines and Terms of Use a be a successful creator!
Let me know your thoughts and if you have other ideas you’d like to discuss. I’m happy to bounce ideas around so we can find the right solution for you!