But I really didn't think this thread would go this way, it was clear to me OP knew his way around a kitchen and was from Europe so knew enough about Italian cooking stereotypes to understand the intended humor.
Fwiw, you learn mother sauces after six weeks of knife skills at Auguste Escoffier in the US so you could definitely be right about 102 :)
Some people go their entire lives 1. not making scratch hollandaise 2. knowing it is a mother sauce 3. adding to the mother sauce to make bearnaise, etc
The part that seemed like gatekeeping was the part where they asserted that "a million Italians [are] crying. Because of you" in response to a commenter describing different methods of making a lasagna that require varying levels of skill.
That seemed like an attempt at gatekeeping because it asserts that many people who are making a lasagna in any way besides their preferred method that relies on "mother sauces" is Wrong.
Someone could also claim the opposite that the “easy” version is cultural appropriation.
Jokes are hard nowadays.