It's not just about the fun of scratching ... it's about protecting the starter codes that could be on cards that sit there at a shelf at a store.

Sure that was understood, something would need to protect the code.

Also I'm fine with (and so should the splinterlands team be fine with) the site (aka splinterlands.com) being out the 15%+ from commissions. The worry is the market taking the hit for the 15%.
Prices of individual cards are very very closely related to things like the 500 pack bulk discount the 5% comission and the 30% DEC-exchange discount.

There's already higher commision rates (its possible to get a 15% rebate at this very moment. I would suggest putting a cap on the max rate someone can get so abuse isn't rampit. For example if an affiliate were to reach the max 15% commision then they wouldn't be able to claim the market commision if they started a market. This would mean the max rev share anyone could get is 15% but there would be multiple ways to reach that 15%.

DEC price shouldn't affect rev share decisions for paying those who are working hard to spread the word of the game. The Devs decided to accept DEC at $1/1000, currently that is working in the players favor as DEC can be attained for cheap but we shouldn't penalize affiliates for that.

If you add higher commissions i think it could be very easy for those to impact the prices of all the cards. How to stop a buyer from also being the seller? Almost impossible in this sort of environment. For example I have bought some packs (mostly i buy individual cards from the market) that makes me both a buyer and a seller (because of peakmonsters)

You can't stop a buyer from being the seller. Affiliate programs have been abused like above for years. Its one of the flaws of the design. Anyone who creates an affiliate program mostly has to just accept that. There have been some sites that will ban you from being an affiliate with them if you sign up under your own link but I know that won't go over well with Splinterlands.

Putting a cap on the commision that is attainable from any single account will protect the game from abuse. In short, No stacking commissions, if someone plans on having secondary market and gets 10% rev share then they can only stack a 5% affiliate bonus on top of that as that would allow them to reach the max 15% rev share.

Affiliates abusing the system can have their rates cut back to 5%.

Also keep in mind this "ambassador" model requires travel to and from these different shops. That's time out of ones day and gas money (which could add up to allot). One would need allot of 5% commisions sales to just cover expenses.