Two points:
1. A release clause serves different purposes. Messi had a release clause, as did Neymar, etc. Doesn't mean anyone could realistic afford them (unless you're PSG). You don't know what Haaland's release clause would've been at United had we signed, him, but I reckon it would've been in the range of where it's at at City (somewhere in the 200 million range). For context, his release clause at Dortmund was 65 million pounds or so, far more attainable, and therefore basically an insurance policy that he could get out for the right price.
2. Where have I said long contracts only protect the clubs? A contract is an agreement between two or more parties. Common sense suggests that the parties in it are in it for themselves. So clearly both club and player, and any third parties, benefit.