You need to think at the system level, and with the time dimension added.
Let's see how it would go down if I followed your advice:
- I use coupons, like everyone else: I then save money
- I take a moral grand stand and refuse to use them: I waste money
- magically (meaning I don't think it'll ever happen), people are inspired by my moral grand stand and almost everybody stops using coupons: everybody saves money
- someone doesn't care about morals, and start using coupon again: they save money
- they post about this "one weird trick", other people decide to join in, they try and realize it helps them save money, I do the same, and we're back to square 1.
And from that point on, more people will be using coupons until almost everybody again uses coupons.
You can't win a fight against the shared preferences of everyone else in the world.
If you think you can, great! Then the best tool is to use politics to legally forbid coupons. If it's such a great idea, you'll certainly have no problem finding a wide popular support for that?
If it's not so popular, then what do you think gives you the right to impose your preferences on the majority?
It may seem better to take this grand stand, but to me, it's pointless: you are just wasting money to feel good, with no chance to do anything else in a larger picture, but feel special or more enlightened.
But if you like it, why not?
The problem is when sites like Amazon require accounts, there is not much to do to get around being tracked and having dynamic pricing come into play. At least with airlines you can VPN and use private browsing to try and avoid this practice.