Welcome and problems
“You’re welcome,” is not the same as, “it’s my pleasure.”
“No problem,” is not the same as, “I’m happy to help.”
These sentences are the closing parentheses of a simple conversation that opens with “thank you.”
We have to say something. The “thank you” demands acknowledgement.
It could be, “okay, now we’re even.”
Or we could express satisfaction at having the ability to make a contribution. We can continue the infinite game instead of simply walking away.
That might be more satisfying all around. A wave is more powerful than a grimace.