It means that stores will be destroying their copies instead of selling them, and SE will pay them 16 bucks for each destroyed copy. Probably.

It's likely to be because SE does not want the old discs to be sold alongside the new ones, and because they want to sell the new copies for 50 bucks. If a store still sold V1, customers could get the game for 10 bucks and still be able to play in V2.

Additionally, people buying V1 to save money like this on purpose, would lead to a lot more people needing to download the client from SEs servers, which would probably cost them more money because they'd need to set up more mirrors.

It's the sensible thing of SE to do. I don't blame them.