I think that's the big qualifier here. The productivity paying off the price is only meaningful if your time and money are arbitrarily fungible for each other, and for most people they are not. There's a good chance they won't be able to find a way to convert that saved time into the corresponding $20+ needed to pay the bill. And if finances are tight, $20/month might be a deal breaker.
Even if you're a freelancer, if your projects have billing caps related to the number of hours you expect to work then you don't necessarily have adequate time/money fungibility. $20 a month also might not be worth the cost of going out and acquiring a new project.