For example, the west portala Sherwood Forest area is essentially a suburb within the city. There are huge lots that are 5000 sq ft when next door neighborhoods you have 1600sq ft lots with 2-3 units. Essentially you have suburb neighborhoods right next to others that have 10x the density.
A developer would love to buy units in those areas and convert to duplexes but is literally impossible to do this.
So again, it's not a question of preserving our parks but a question of preserving our suburbs within the city so rich people get to live in a suburb within the city and watch their property prices skyrocket instead of allowing the city to expand and accommodate the middle class.