Exclusivity contracts are very, very common in the business world and are even a necessity to control costs for suppliers, distributors, retailers, and consumers. The "problem" is that to what extent are these practices "wrong" for large companies aka "monopolies."
Just follow the chain. Intel, by contractually obtaining, a huge set percentage of a companies business guarantees reaching certain capacity, cash flow, and revenue. This, inturn, allows Intel to give rebates to Dell/HP not offered to non-exclusive partners and those not operating with these sort of volumes. This allows Dell/HP to be more competitive/larger volumes. The rebates help Dell/HP compete more competitively and target bigger customers and helps Intel because their biggest partners are more comeptitive. Distributors and Retailers get competitive pricing on well marketed "brand" product and can purchase from large companies that have significant infrastructure for both product and product support. Consumers gain the advantage of availability and product quality.
So remove the contracts and the chain is damaged. AMD wasn't/isn't capable of providing product at the scale/timeframe expected, Intel no longer offers rebates to Dell/HP because as volume goes down/costs go up. Distributors/Retailers pay more and in the end consumers may as well.
Interestingly, AMD could have simply created programs that offered Dell/HP the same volume with better pricing. But they couldn't (and cannot). Consumers (and the idiot EU) need to understand that business is more than just benchmarks in some game = desirability in the business-to-customer channels. Availability is huge as is guaranteed pricing. It doesn't matter how good your product is if it isn't available when the customer wants it.
Now Intel would have avoided some of this hurt if the contracts were volume based. i.e. "For X rebate Dell must purchase 25M Intel CPUs." Obviously we would be quite unfair to cast a blind eye at co-marketing and brand placement, mutually beneficial business arrangements for exclusive contracts, etc. The business world thrives on such and it is completely legal ... as long as you are not a massive company with significant marketshare and deep pockets. While I wouldn't argue that these contracts are always better for consumers, it would be wrong to argue they are always harmful. Likewise they can be quite beneficial to businesses and longterm industry health.
It would be curious to inquire of AMD and the EU if they have any exclusive contracts with any customer that gains them a benefit. I bet they both do and I bet in some of the case that it isn't completely in the benefit of the end consumer.