I see Phil Spencer as a business man running a business. Indie devs don't have a right to release games on whatever platforms they want to, whenever they want to, however they want to. This is how the business world works. I can't open up my own hotdog shop in the local mall tomorrow because I want to. The mall has rules in place for entry, and I can only get in if I follow the rules they've put in place.
Unless the local mall is run by Microsoft, in which case they will cut you a backroom deal to let you bypass the building code if you're popular, right?
The rules are being pointed out as harmful. Not to mention that other, similar, more popular platforms are not imposing these rules. Which highlights how arbitrarily they're being applied.
Microsoft has rules in place for releasing a game on their platform. Is it harming the platform? I kinda doubt it, as the guy in charge clearly has decided to keep the policy in place despite some complaints. He's also made it clear that they'll bend the policy in certain situations where they think it's best for them to do so. So it's not 100% rigid.
It clearly isn't working, as shown by the reaction from potential business partners and the market.