Why don't millennials say you're welcome?

Why is it that millennials, who are often known for their politeness and good manners, often refrain from saying "you're welcome" in response to expressions of gratitude? Is it a generational shift in social norms, or perhaps a cultural shift influenced by the rise of technology and social media? Are millennials more likely to view acts of kindness as being inherent to society, and therefore not requiring explicit acknowledgement? Or could it simply be a matter of personal preference and communication style? As a cryptocurrency and finance professional, I understand the importance of understanding social trends and dynamics, and I'm curious to hear your thoughts on this topic.