Why do we need multiplexer?

Can you please elaborate on the importance of multiplexers in today's technological landscape? Why is it crucial for us to have them, and what specific challenges or limitations do they help to address? How do they contribute to the efficiency and functionality of electronic systems, and what are some of the key applications where they play a vital role? Additionally, could you discuss any potential future developments or advancements in multiplexer technology that may further enhance their capabilities and benefits?