They mean plenty, they just require you apply some critical thinking...
5$ to 50$ is not 10 servers on Heroku. In fact, it's not even one server, you'll be sharing resources at that price point.
Let's say you generate approx. 500 lbs of CO2 a year (based of figures for a half desktop PC running 24/7 because you're only getting 2 cores and 1GB of ram)
At this point you're thinking, 500lbs?! That's insane!
But 40 hrs (1 week) is a lot of time, and 500lbs of CO2 is less than it seems.
If you spent 40hrs spread out over an entire year air drying your clothes a total of 20 times, you'd save over 2 Tons of CO2 a year. (You can do the math for a dishwasher if air drying doesn't work where you are)
If you live in a cold climate, the EPA estimates you can save 15%, or almost 1000 lbs of CO2, by weather proofing your home, easily accomplished in 40hrs
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You might say "I already do all these things!", but the point is there are so many ways to convert time to CO2 savings.
We spend a lot of CO2 trying to save time you could say.
Optimizing your bootstrapped service is not one of the places I would use CO2 expenditure as reasoning in the slightest.