If you want economy/coach awards, it is more reliable to use a 1% cash back card and save your money.

Some people want miles because they want business class awards or upgrades. That is a value judgment. Use of miles for that is worthwhile if you think "see how much money I saved". Use of miles for this is not worthwhile if you think "this is not the most economical way of going from ORD to CDG".

If you use rewards cards (miles or cash back), you are screwing the small business. They are forced by credit card companies to pay all of the rewards and then some. The only way they can refuse is if they refuse to take credit cards at all. That would be like a rule saying in order to accept plumbing, you also have to accept an ex-convict to live in your home. You could reject the ex-convict but then you can't get any plumbing. Credit card companies would offer 50% cash back if they could get away with it.