“No problem” seems to have replaced “you’re welcome” as a response to the common expression of gratitude, “Thank you.” Since communication is a two-way proposition, “no problem” has implications for the hearer.
“It didn’t cost me anything.” “No big deal.” “If it had been too difficult or costly, I may not have done it.”
“It was easy to do.” “I would have done it for anyone.” “I didn’t think about it too much.”
“No sweat.” “Anyone could have done it.” “Nothing particularly important happened; no biggee.”
“No problem” seems to ignore the gratitude of the other person. It is a blah word that blows an opportunity to respond with care to another person. “No problem” is often deaf and does not acknowledge the gratitude of the expressor.
On the other hand, “you’re welcome” receives rather than deflects a thankful heart. It is the simplest way to respond to and acknowledge gratitude.
“I was happy to do it” says that the act was intentional. The deed was not just some random act done without any particular interest in the other.
In a world that is often rude and inconsiderate, a simple “you’re welcome” is a way to drive back incivility, build relationships, and make another person feel affirmed.