Good. I own and use an apartment where the majority of the building is short term holiday rentals, and these people flout security, noise ordinance, facilities and are a general nuisance through and through.
We learn theory not to understand the derivation of the details, but to understand how the theory fits in with everything else. Using a library without understanding the theory just means you know that sin(angle) is just a number, but not how the number helps you work out the length of steel beam as it changes due to changes in angle.
They are simply not the same.
Source: working with juniors that can't do anything outside of what the libraries do for them.
Just ignore them. They open with ad hominem attacks, or myriad assumptions about age, account credibiltiy based on registration date, nationality vs ethnicity, political leanings, etc. and demand your response. Let them stew in their ignorant hate.
It's the sacred responsibility of every dad