Pollution can take the form of chemical substances or energy, such as noise, heat or light. Engines are noisy and hot. Why shouldn't they pollute?

For me, limitations presented by belts, pipes, etc. in Factorio are what keeps it interesting. If you don't have to think about the consequences of putting down a pipe in that particular place, then the game has lost something.

Just my 2c.

It would solve that problem, but it wouldn't solve the oil barrel problem. All the limit does is artificially reduce the number of stacks. A smart wagon arrangement would allow you to control the stock of the wagon without limiting its stack number.

Yep, every time I think I'm "finished" with Factorio there's another major release, and it feels twice as good as it was. Oil is fantastic.