This has age old debate about "tip the minimum no matter what" and "tip extra and get better service" since I first got on review sites back in 2014. You will never change anyone's mind, but I know that for some reason I usually get the top of the line service and always tipped accordingly. It really works out especially when you like to repeat with the girls that give the best service. And I personally thing that the upgrade in tips has improved the service all around. Things that are given more freely now, you had to earn them in the past with an extra tip and/or being a regular customer.
If you want to shop price in Philly go to Saigon or French. In the burbs you will not find the bargain spas so if you want to tip the minimum then just be happy with a little diluted service. I don't think there is any reason to get riled up, it's just that the facts are the facts.