My favorite quote that expresses this idea is from Mikhail Kalashnikov, designer of the AK-47: “Before attempting to create something new, it is vital to have a good appreciation of everything that already exists in this field.”

A good example of why this is true I see in my bubble is in Indie tabletop RPGs. Fairly regularly if you follow indie rpg websites and forums, you get the following "I am sick of how Dungeons and Dragons does X so I made a new system". They will then proceed to describe Dungeons and Dragons but with some half-baked idea that is already done in some other game. So you might say "Hey this is already done in Traveller". But the people who have extremely little exposure to the field, and have only ever played one game (D&D typically) ends up re-exploring the field with "new ideas" that have existed for decades and have already been iterated upon.

And then, if you are great, you will steal not from one thing but from everything

there is negative stealing or avoiding mistakes done by others. as propounded by Warren Buffet and others. and epitomized by philosophy of being less wrong.