There are five different sites in Delve that these rules pertain to. Understanding how they work and differ from each other will help you understand why the rules we have for them are what they are.
New gas sites spawn after downtime, or shortly after a previous site has been cleared in the same constellation.
When a gas harvester cycles on a gas cloud, the cloud has a chance explode, dealing between 1500 and 2000 EM/Thermal damage to all ships within range. Due to this, the DPS of the clouds increases linearly with the amount of ships huffing them.
Crab, Hazy and Whirling nebulas all have rat spawns significant enough to existentially threaten a single huffing ship.
Hazy nebula's explosions can be completely avoided by staying at range from the cloud as you huff. If you do not, you will most likely die.
—–