I agree with you to some extent. Let me clarify 3 points:
  1. This policy applies at the pool level, not the protocol level.
  2. Some pools currently block transactions using undisclosed filters, it is not a technical challenge to do so with the current software
  3. QoS manages priorities; it doesn't prevent transactions from going through at some point
If this system becomes a standard solution that fixes the congestion issue, dishonest pools can't use censorship as a pretext for solving problems. I'm not suggesting that there are currently pools engaging in this behavior, but I believe the overton window has been opened.