A theory and explication relating to the use of "no problem"

I do not like it when I thank a young person for doing something and they say "No problem".  We ourselves use the phrase when asked to do something and we are willing and happy to do it.  In those circumstances, doing the requested act is not a problem.  That is, it is easy and even a a pleasure to do something for the other person.  So, here's the rule: for older people, say "No problem" before something is done but you are willing and able to fulfill the request.  But, and this is important, say "you are welcome" or "it was my pleasure", something other than implying that you only helped so long as it was "nothing" and took little or no effort.  I realize that is some cultures, it is standard good manners to say something equivalent to "it is nothing", meaning "Oh, what I did is very little, not worth mentioning", that is, a type of modesty about the favor done.  But we prefer not to be told that we are nothing, that the favor we take pleasure in receiving is actually a miniscule thing and by extension, we too hardly matter.  This whole subject is not a big deal when considered from the larger perspective of centuries but if you want a good-sized tip, don't relegate us to tinyness.