It's one of those American pieces of technoslang, except that it's probably some 100 years old. It's about the difference between cooking on a wood stove, and cooking on a natural gas rangetop.
With the wood stove, there's building the fire, and then modulating the heat with the dampers, flue, and fuel. It takes about 20 minutes to get the thing hot enough to boil water, so most folks kept the thing running all day. Accordingly, the kitchen was very, very hot - all the time. Thus, "if you can't take the heat, get out of the kitchen." The risk of fire was great - many larger homes had the kitchen in a detached outbuilding. Poor folks just had to deal with the distinct possibility of your house burning down.
Compare all this to cooking with gas. No hauling wood, no lighting a fire. Just turn the knob, a miracle. Natural gas burns with great heat and efficiency - so no odor, just CO2, and huge transfer of thermal energy to what you're cooking. Water boils fast! It's the original "instant on" tech - no boot time. And you can modulate the heat with great control. Imagine all this, suddenly in your kitchen, replacing the belching, flaming monster that you've struggled with every morning and night. It would seem... modern, efficient, an consumer-industrial miracle. It would make the past seem slow and antiquated. If something truly kicked ass, if your thoughput suddenly jumped through the roof, you were cooking with gas.