In Europe, by law it is the retailer responsible for warranty claims.

Many manufacturers will also offer warranty service, and it is up to you the customer which you want to use. Often manufacturers try to persuade you to contact them first because it costs them less than a refund would (typically retailers just refund rather than attempt a repair or replacement)

The law requires the retailer to deal with warranty claims. The law also requires a 2 year warranty minimum. Additionally a retailer must take back old electronics and recycle them at no cost to the customer.

The idea is that as a consumer, I made a contract of sale with the retailer, not the manufacturer or anyone else. So, if there's a problem I go to the entity I have the contract with, i.e. the retailer.

You can often claim warranty with the manufacturer if you want; depending on the item. It can be faster to do so, but you're not required.