The sink is a long term use product - stainless steel is exceptionally strong and won't be damaged over time.
The sink are often exposed to water - stainless steel will not be corroded nor rust.
The sink is also used to deal with hot pot, hot water and so on - the stainless steel has the thermal protection function, does not melt and does not burn. Expensive glass products should also be washed in the sink-stainless steel will not wear out the broken galss and porcelain.
The sink is exposed to the sunlight outside the window every day - the stainless steel is not affected by the strong light.
The sink is a part of the home environment - the beauty of stainless steel is tasteful.
A lot of food should be washed in the sink - stainless steel is easy to clean and very sanitary.