The big ones fill an important role too and usually became big by being very good at what they do. Often, small businesses are appalling employers. When DH left the Army, he worked for many small contracting firms and the attitude was always put up with terrible working conditions, lack of safety equipment and very long hours or leave, no sick pay etc. Since then he's worked for two multinationals who take staff wellbeing etc seriously.
DS1 works for McDonalds who treat him far better than friends working in small local cafes and their hygiene practices are top notch, when smaller businesses can be hit and miss.
When you find a good small business, they are like gold but a lot of them just aren't very good and the bigger ones are important employers in the communities in which they operate.