Why do people not combine smaller telescopes. For instance 8 inch dobsonians are cheap, but a 16 inch is thousands of dollars. They combine the light gathering ability of large telescope to make one image with double the aperture.

Why can we not do it with small telescopes? It is also easier to take care of a few 8 inch scopes than one larger one and the mirrors cool down faster due to temperature change

why?

https://www.eso.org/public/teles-instr/paranal-observatory/vlt/