Real-world systems differ a lot from the textbook theoretical system designs.

As I'm reading about system design concepts, I do understand how crucial they are for designing a fine system depending upon the scale of users.

Comparing those concepts to what I see in my company, these differ a lot. Real-world systems are the ones that are in the millions of dollars and able to generate revenue and aren't as closely ideal as the theoretical concepts.

Those are the ones that are actually generating revenue and traffic.

Riddled with hacks by the people who developed them to handle unknown situations. These differ vastly from the theoretical concepts, so even reading about system design concepts feels kinda redundant